The Cardiac Consequence of Sound

Waterfalls are a wonder of nature. They are often the prizes found after a long hike through the woods. Waterfalls are a worldwide phenomenon. However, the number of waterfalls are not easy to determine due to differing definitions; California is estimated to have as many as 400. The world’s longest waterfall is Angel Falls in Venezuela at 3212 feet; the tallest waterfall in the US is Yosemite Falls at 2425 feet. Victoria Falls in Zimbabwe is felt to be the largest at 5604 feet wide and 304 feet high. Its roar can be heard 25 miles away!  Waterfalls are nice to look at, but if you live near one would the constant roar of the water be soothing or annoying?

Sound is measured in decibels.  Decibels for some common sounds include normal conversation which is 60 decibels, whispering is 20 decibels, and a rock concert is 110 decibels. Constant exposure (more than 8 hours a day) to sounds over 85 decibels is considered hazardous and unhealthy. Noise is sound that is perceived as annoying.  Noise pollution, or environmental noise, is noise that affects a person’s health or behavior.  Many studies have shown that environmental pollution in the form of traffic noise (from cars, airplanes or trains) is associated with heart disease. Traffic noise confers an increased risk for high blood pressure, heart attack, stroke, atrial fibrillation and congestive heart failure.  Constant traffic noise increases the risk for high blood pressure starting at 45 decibels and increases every 5 decibels. Heart artery disease starts to occur with continued exposure to noise at 50 decibels and increases each 5 decibels in the evening and 10 decibels at night. The constant annoyance of traffic noise causes a stress reaction. It disturbs sleep, increases adrenaline, releases stress hormones, raises blood pressure and alters blood sugar and cholesterol metabolism. The effect is stronger if the noise occurs at night. Nighttime aircraft noise increases blood pressure further and heart disease is more strongly associated with people whose bedrooms face the road.   Unfortunately, noise pollution often goes hand in hand with air pollution. It may be difficult to determine which is the cause for heart disease: noise or air pollutants. There are other circumstances where noise may be implicated in heart disease. People who have long-term exposure to loud noise at work are two times more likely to have heart artery disease.  The intensive care unit (ICU) is another area where noise pollution is a factor. ICUs are noisy places; alarms go off, IV pumps beep and there is 24 hour per day chatter among the ICU personnel. The noise level in ICUs is a constant 50 to 75 decibels, even at night. Thus, sleep disturbance is a common problem for ICU patients. In addition, noise pollution in the ICU is associated with delirium (confusion) and worse outcomes among patients. 

Not all sound is bad for the heart. Music and sounds from nature may be beneficial for the heart. Listening to music may help heart patients by decreasing heart rate and blood pressure, relaxing arteries and improving blood flow and reducing stress. For example, patients who listened to music after heart surgery had less pain and less anxiety.   Music, however, is very personal; what one person perceives as soothing, another may find annoying.  Despite that, neuroscientists were able to test a number of songs on their ability to reduce anxiety. Their research produced a playlist of the most relaxing songs on earth.  Are nature sounds just as soothing as music? Not much is known about sounds found in nature. One group had patients undergoing heart bypass surgery listen to nature sounds (birds chirping, waves on the beach, jungle sounds and the sound of rain).  They found that natural sounds were able to reduce anxiety in patients around the time of surgery. 

So, are waterfalls soothing sounds from nature or noise pollution?  Consider the case of Niagara Falls, New York, one of the largest waterfalls in the world and one whose noise level is a constant 95 decibels.  According to an article in the Buffalo News from December 2016, the Buffalo Niagara area has one of the highest rates of heart attacks in the country.  There may be many reasons for that, but could it be from noise pollution from the Falls?  More research is needed on this question, but if you are planning to visit, consider bringing your noise cancelling headphones.

What's Your Score?

At the dawn of a new decade, what is the best way to assess a person’s risk for atherosclerosis (plaque in the heart arteries)? There are many different tools to choose from including several risk calculators, blood tests (for example C reactive protein) and imaging tests (such as stress tests or ultrasound of the neck arteries to determine if plaque is present). Of all of the approaches available, what is the optimal approach for someone who may have coronary artery disease? 

The first step is to see a doctor, have a good physical examination and basic laboratory tests, including total cholesterol and LDL cholesterol (the “bad” cholesterol).  If the total cholesterol is over 200 or the LDL is over 100, the next step is to enter the data into the American College of Cardiology risk calculator (cvriskcalculator.com).  The calculator will give an estimate of the chance of a heart attack or stroke within the next 10 years.  The estimate can be broken into four categories:

Low Risk: 0- 5%

Borderline Risk: 5-7.5%

Intermediate Risk: 7.5-20%

High Risk > 20%

Low risk patients need no further testing or medication, but should continue with a heart healthy lifestyle. High risk patients should be started on aspirin, blood pressure medication (if appropriate) and a statin to reduce cholesterol. For those in the borderline and intermediate categories, additional consideration is needed. The next step is to assess whether the patient has other risk enhancers. These include:

LDL > 160 mg/dl,

high-sensitivity C reactive protein level (a measure of inflammation) > 2.0 mg/L, 

triglycerides > 175 mg/dl, 

peripheral arterial disease, 

chronic kidney disease, 

chronic inflammatory disease (rheumatoid arthritis, psoriasis, or lupus), 

metabolic syndrome (hypertension, diabetes, high triglycerides, obesity), 

family history of premature heart disease, or 

premature menopause

For the patient with borderline or intermediate risk and the presence of one or more risk enhancer, a statin should be initiated. If there is still uncertainty about starting medication or the patient is reluctant, the next step is to do a coronary calcium score. The coronary calcium score is obtained with a computed tomography (CT) scan. No contrast is used, so there is no preparation and no intravenous line is needed. The patient goes into the CT scanner, holds their breath and the scan is obtained. The whole process takes only a few minutes.  The down side of the scan is that a small dose of radiation is used and in many cases insurance doesn’t cover the cost. Fortunately, locally, the cost for a coronary calcium score is just $99. The scan measures the plaque burden in the heart arteries.  Plaque is formed by cholesterol deposition followed by inflammation and calcium build up. The scan can detect and quantify the amount of calcium seen in the heart arteries. The coronary calcium score is the sum of all of the calcium seen in all of the heart arteries. However, the scan does not show the amount of blockage in the arteries (plaque may be present only in the wall of the artery or it may be part of a plaque causing blockage to blood flow).  A coronary calcium score of 0 means there is no plaque in the heart arteries and the patient is at very low risk for a future heart attack. No statin is recommended. A calcium score between 1 and 99 means there is plaque present and a statin should be considered, especially for patients older than 55.  For patients with a coronary calcium score over 100, a statin is indicated and further testing, such as a nuclear stress test should be done to see if the plaque is causing significant blockage. 

It is important to realize that this approach is only for patients who do not have heart artery disease (primary prevention). For those with a history of disease (a heart attack or stroke, heart bypass surgery or a heart stent) or those who have diabetes with an LDL over 70, this approach should not be used and those patients should be on a statin. In addition, this approach is only for adults between the ages of 40 and 75.

What about patients who are 75 years old or older? Should they be on a statin? The risk for cardiovascular disease increases with older age. Taking a statin may help reduce that risk. On the other hand, other diseases (such as cancer or dementia) also rise with advancing age and limit the benefit of statins.  For patients with a history of heart attack, stroke or cardiac revascularization (secondary prevention), the data is clear: continue the statin, even in the very elderly.  For primary prevention in those over age 75 the data is less clear.  A recent trial of patients over 70 years old showed a lower risk of dying from any cause for those on statin versus those who were not on statin. In addition, the statin patients had fewer heart attacks and strokes.  Another study looked at patients over 75 who had their statin stopped.  The participants who came off their statin were at higher risk for hospitalization and cardiovascular events.  One of the reasons for stopping a statin in older patients is the perception that statins increase the risk for dementia. However, there never has been an increased risk for dementia in all of the studies done on statins. A recent study of statin patients 70 to 90 years old confirmed that there was no increased risk for dementia.  In fact the statin patients showed less cognitive decline, suggesting statins may be protective for brain function. 

So, take the steps necessary to reduce your risk for heart artery disease. If you are between 40 and 75 years old, see your doctor, have blood work, calculate your 10 year risk and see if a coronary calcium score is right for you. If you are over 75 years old, don’t stop the statin and discuss with your doctor the pros and cons of continuing medications. 

The Cardiac Christmas Catalogue

What should you get for the heart patient who has everything this holiday season? Technology and digital health are all the rage. Since 2013 the number of people tracking their health data has doubled. Wearable electronic devices can capture a wide range of health data and can be very useful for the health of and the care of the heart patient.  Wearable devices have sensors that are incorporated into a watch or clothing or can be worn like a vest.  What kind of wearables are available for the heart patient in your life?

Fitbit

Apple Watch

Kersh activity monitor

Kionix Accelerometer

SenseWear Pro3 armband

Zephyr BioHarness:

These accelerometers can measure activity and mobility. The devices estimate step counts or the number of miles walked per day. This can be very helpful for the individual to track his or her own activity.  They can differentiate between exercise and standing. Workouts (such as running or cycling) can also be tracked. In addition, the Apple watch has a heart rate monitor and there are available apps which are designed for sleep tracking (measuring sleep time, breathing and snoring).  These features are useful not only for the individual, but they have medical applications.  The accelerometers are being used to monitor cardiac rehab patients and patients with congestive heart failure, with real time interventions to keep the patient active and moving. 

Apple Watch 4 and 5, AliveCor:

The Apple watch uses light sensor technology to see if there are irregular contractions of the heart. If so, an algorithm decides if there is atrial fibrillation (Afib, an irregular rhythm from the upper chambers of the heart).  The AliveCor device has a small external monitor with two electrodes. The patient places two fingers on each electode and an electrocardiogram (EKG) is recorded. Again an algorithm can help decide if Afib is present.  How accurate are these devices in detecting Afib? The Apple Heart Study was a huge study (more than 400,000 participants) recently published in the New England Journal of Medicine. The study claims that the watch was 84% accurate in diagnosing Afib.  This sounds impressive, but the study has flaws.  Only 6% of the participants were over age 65 (the age group most at risk for Afib) while 52% were under 40 years old (a very low risk population).  The Apple watch found an irregular pulse in only 0.16% of those under 40, most of whom did not have Afib on further testing.  In the over 65 age group, 3.2% had an irregular pulse, but again only a small number had Afib.  In all, only a few hundred participants among the more than 400,000 actually were diagnosed with Afib.  We don’t know whether these few hundred participants had clinically significant Afib  (meaning that medications needed to be added or adjusted for the Afib). While the technology seems promising, it needs to be tested in a population that is prone to Afib. 

Omron Heart Guide:

This device is a wrist-based wearable that takes blood pressure (BP).  The smartwatch has a secondary, inflatable strap that works like a small BP cuff on the wrist.  To take a BP reading, the arm is held at chest level and a button is pressed. The BP is displayed, along with a notification (green if the BP is good, red if the BP is high).  It has been shown that BP taken at home is more accurate and more predictable of cardiac outcomes than BP taken in a doctor’s office.  So this device may make a difference for the hypertensive patient. In addition, this device gives 24 hour BP trends, which have also shown to be important. On the plus side, this wearable was approved for use by the Food and Drug Administration (FDA).  On the other hand, it is bigger and heavier than an average smartwatch and it is quite expensive ($500). 

ReDS vest:

This wearable may be beneficial in the detection of and management of congestive heart failure (CHF). CHF occurs when the lungs fill up with fluid.  In the United States, CHF is the most common reason for hospitalization.   The ability to detect fluid build up in the lungs before full-blown CHF occurs would be a major advance for patients, avoiding many hospital stays.  This device works on dielectric principles to estimate the fluid level in the lungs. The vest sensors do not require skin contact and can be worn over clothing. The vest calculates fluid volume in 90 seconds and relays the information to the patient’s doctor. If fluid is accumulating, medication can be adjusted before the patient runs into trouble.  In a study of CHF patients, the ReDS vest reduced hospitalization by 87%.  The vest is FDA approved and commercially available.

Life Vest:

CHF patients with weakened heart muscles are especially prone to sudden cardiac arrest, an irregular rhythm from the lower chambers of the heart. Sudden cardiac arrest is deadly unless the heart is promptly (within 10 minutes) defibrillated (shocked back into normal rhythm).  The automatic implantable cardiac defibrillator (AICD) is a device that is implanted in a patient and can detect these irregular rhythms and internally shock the heart back to normal. The AICD has been shown to save lives. However, there is often a period of several months between the diagnosis of a weakened heart muscle or a heart attack and AICD implantation.  This is where the Life Vest steps in. The Life Vest is worn 24 hours per day and requires skin contact.  It can detect and shock a patient who is in sudden cardiac arrest.  The VEST trial showed a 35% reduction in death between those who wore a Life Vest and those who didn’t. The Life Vest is currently being used as a bridge. If a patient’s heart recovers after an acute event then an AICD my not be needed. If the heart doesn’t recover, the patient is protected and an AICD is placed.

Happy shopping!

Presidential Heart Disease

Election day has come and gone. Next up we will be voting for the White House occupant for the following four years. As a group, the Presidents have generally been healthier than the average American. However, as Bernie Sanders’ recent heart attack made clear, the Presidents are not immune to heart disease and stroke. What is the history of Presidential heart disease and what lessons can the average citizen take from history?

We’ll start our Presidential heart history with Woodrow Wilson. In 1919, during his second term, Wilson suffered a stroke. Despite being paralyzed on his left side he was able to complete his term.  Warren Harding was President from 1921 to 1923. He died of an apparent heart attack and cardiac arrest while in office in 1923. The man who took over for Harding, Calvin Coolidge, was President from 1923 until 1929.  He died from a heart attack in 1933. During Franklin Roosevelt’s third term in office, in 1944, he was diagnosed with high blood pressure, coronary artery disease and congestive heart failure.  At the time, there were no effective blood pressure medications so his systolic blood pressure was routinely over 200 and often 250.  Despite his health problems, he won a fourth term, but died from a massive stroke in 1945.  1955 was not a good year for Presidential heart disease. Dwight Eisenhower suffered a heart attack while in office and future president, Lyndon Johnson, also had a heart attack that same year.  Both men were treated, as was the custom at that time, with one month of bed rest. Both men were heavy smokers at the time of their heart attacks. Eisenhower would go on to have seven heart attacks and one stroke. He died from congestive heart failure in 1969.  Johnson had another heart attack in 1972 and died from a heart attack in 1973.  During his term in office, in May 1991, George H. W. Bush was diagnosed with atrial fibrillation (an irregular rhythm from the upper chamber of the heart).  His heart was electrically shocked back into rhythm.  Bill Clinton started having chest pain three years after leaving office and ultimately underwent open-heart bypass surgery.  Lastly, George W. Bush was found to have a blocked heart artery in 2013, four years after the presidency. He was treated with an angioplasty. 

In all, nine of the last eighteen Presidents suffered from heart disease or stroke, a prevalence of 50%, which is much higher than the average rate of heart disease in Americans. Why is this? Many of the Presidents had risk factors for heart disease such as high blood pressure, high cholesterol or diabetes. Many were noted heavy cigarette smokers.  In addition, one can imagine that these men were under a tremendous amount of mental stress.

Mental and emotional stresses have long been associated with heart disease. When these stressors occur, there are a number of physiological changes that are detrimental to the heart.  These changes include an increase in heart and blood pressure, as well as an increase in the heart’s demand for oxygen and blood flow. The heart arteries can close down or spasm, reducing blood flow to the heart. There is increased inflammation and various clotting factors are activated. In addition, mental stress causes behavioral changes. Under stress, patients may go back to smoking, consume extra alcohol, not follow a prudent diet and stop exercising.  Cardiac hyperresponsiveness from mental stress has been associated with an increased risk for high blood pressure, atherosclerosis, heart attack and cardiac death.  Patients experiencing mental stress can have chest pain, but more worrisome, mental stress is often present without symptoms. The medical term for this is “silent ischemia” (ischemia is lack of blood flow to the heart). Ischemia from mental stress can be detected with an EKG monitor or during a mental stress test. A mental stress test is performed by applying EKG leads and, instead of walking on a treadmill, the patient is asked to perform a task such as solving a tough math problem, or public speaking, or naming all of the Presidents. The mental stress test can be combined with nuclear or echo imaging as well. 

So how can the average American citizen avoid following the Presidents down their adverse heart heritage trail? First, take care of risk factors. Avoid smoking, exercise regularly, follow a good diet, keep weight down and treat high blood pressure, diabetes and high cholesterol. As difficult as that is, managing stress may be even more problematic. There is a lot of stress in our daily lives. From small stressors (for example, traffic congestion) to larger issues (such as job or family stress), stress is ubiquitous and nearly impossible to avoid.  That is why stress management is such an integral part of cardiac rehab programs for patients with heart disease.  Interventions need to be long term (over at least 6 to 12 months), be conducted in groups and use techniques that alter the stress response including behavioral training, biofeedback, meditation, relaxation techniques, regular physical exercise and yoga. Lastly, don’t run for President. 

QT: Questioning That Quality Therapy

Antibiotics are one of the great achievements of the 20^thcentury.  In 1900, the top three causes of death were infectious diseases: respiratory infections (pneumonia and flu), gastrointestinal infections and tuberculosis. Starting with the discovery of penicillin in 1928 by Sir Alexander Fleming and the subsequent development of other antibiotics, many bacterial infections could be cured and deaths due to infection plummeted. By 1950, heart disease had become the nation’s number one killer. The term antibiosis comes from the Greek “anti” (against) and “bios” (life) or antilife. In this context it means the killing of bacteria.  Louis Pasteur described antibiosis in 1877 and Selman Waksman, a Rutgers professor, coined the term “antibiotic” in 1942.  While revolutionary and paradigm changing, antibiotics are not a panacea.  There are significant side effects from antibiotics.  For example, one can develop an allergic reaction to an antibiotic. Allergic reactions can range from relatively benign (rash) to life threatening (anaphylaxis). Symptoms of anaphylaxis include hives, swelling of the tongue and throat, low blood pressure, shock and death.  Another major issue with antibiotics is resistance. As bacteria are exposed to an antibiotic, they mutate and become resistant, they no longer are killed by the antibiotic.  This has led to multi-resistant organisms, no antibiotic exists which can kill these bacteria.  This has been the direct consequence of overuse of antibiotics and has become a public health crisis.  Antibiotics can also cause heart side effects. There are two classes of antibiotics which can affect the heart, macrolides and fluroquinolones.

Macrolides are among the most widely used antibiotics and are first line therapy for many respiratory and skin infections. Examples of macrolide antibiotics include erythromycin, clarithromycin (Biaxin) and azithromycin (Zithromax). Numerous studies have shown that using macrolide antibiotics increases the risk for ventricular tachycardia (VT), a serious rhythm disturbance from the lower chambers of the heart and sudden cardiac death (SCD).  These arrhythmias only occur when taking the antibiotic; the risk disappears after medication use is stopped.  Importantly, patients taking penicillin or amoxicillin did not experience VT or SCD.  Approximately 1 out of 8,500 patients taking a macrolide antibiotic will have VT and 1 in 30,000 will have SCD. The cardiac arrhythmia effect of macrolide antibiotics is felt due to QT interval prolongation. The QT interval is a measurement made on an electrocardiogram.  It represents the electrical activation and pumping of the left ventricle, the main pumping chamber of the heart. The Q wave is the beginning of the heart’s contraction.  During the T wave, the heart is relaxing and the electric activity is resetting.  If the QT interval is prolonged, then the ventricle can be irritable and go into an arrhythmia. If the ventricular arrhythmia is not treated (with medications or an electric shock) then death may occur. Patients may be born with a prolonged QT interval, or it can be acquired. Risk factors for QT prolongation include female sex, low blood levels of potassium or magnesium and medications.  Many medications affect the QT interval including anti- rhythm agents (for example, amiodarone, sotalol), psychiatric drugs and antibiotics. 

Flouroquinolone antibiotics are also one of the most widely prescribed classes of antibiotics and are used to treat many infections. The most studied is ciprofloxacin (Cipro). These antibiotics also increase the risk for VT and SCD similar to macrolides and by the same mechanism, prolonging the QT interval. In addition, the flouroquinolones, damage connective tissue in the body. Connective tissue is a supporting structure for the heart valves and the aorta, the main artery from the heart. Because of this, the flouroquinolones have been associated with leaking of the aortic and mitral valves.  In addition, they can cause an enlargement of the aorta (an aneurysm) which can subsequently lead to a tear in the wall of the aorta (a life threatening problem called aortic dissection). 

How can you avoid the serious cardiac side effects of antibiotics? First and foremost, and for many reasons, antibiotics should be used judiciously and only when needed.  Secondly, check to see if you are on another medication which also prolongs the QT interval by going to the website www.qtdrugs.org. If so, alert your doctor and consider another antibiotic. Third, some perspective.  Macrolides and fluroquinolones are still good antibiotics and the risk for a significant arrhythmia is very small. Alternative antibiotics can be used, but any medication can have side effects. For example, the risk of anaphylaxis with penicillin is 1 in 5,000 and the risk of dying from anaphylaxis is 1 in 50,000. This compares favorably to the 1 in 8,500 risk for arrhythmias and 1 in 30,000 risk for dying with antibiotics.  To put the 1 in 8,500 risk in perspective consider that you would need to take an antibiotic every day for 23 years and, on one of those days, you might develop an arrhythmia. So be safe, be querying, but don’t quit that quality therapeutic.

A Bayesian Approach to the Diagnosis of Hypertrophic Cardiomyopathy During Athlete Screening

Screening athletes for causes of sudden cardiac death (SCD) is difficult. The conditions that cause SCD are rare and sometimes difficult to diagnose, especially in athletes under 35 years old. Many hundreds of athletes must be screened to find even a single case of a potentially lethal heart condition. In many series of SCD in athletes, hypertrophic cardiomyopathy (HCM) is a leading cause (1). There are characteristics of HCM that can be detected by the history (syncope, family history), physical exam (a systolic murmur louder on Valsalva maneuver) and by electrocardiogram (EKG).  In addition, it can be detected easily on echocardiography (echo), even a quick screening echo.  Therefore, since HCM can be deadly and since it can be detected using information available at a routine screening, the diagnosis must be made. Would an additional tool, such as Bayesian analysis, be helpful in diagnosing HCM during an athlete screening session?

Bayes Theorem is useful when trying to make a diagnosis under uncertainty.  It closely follows clinical medicine; as information is received, the probability of the diagnosis is revised either upward or downward. Bayes Theorem requires three inputs: a pretest probability (or prevalence of disease), the sensitivity of a finding or a test and the specificity of the finding or test.  It works as follows. A patient comes to a doctor’s office and a disease is suspected. The history is taken and the patient reports a symptom. The doctor knows the prevalence of the disease in the population and looks up the sensitivity and specificity of the finding in picking out the disease entity.  The numbers are put in Bayes formula and a posttest probability is calculated. In other words, the patient is suspected of having a disease, reports a symptom consistent with the disease and the doctor’s suspicion of the disease then increases. If the patient has a physical finding consistent with a disease, then the posttest probability just calculated now becomes the pretest probability and the sensitivity and specificity of the physical finding are used to find a new posttest probability.  If the patient then has an abnormal EKG, then previous posttest probability and the sensitivity and specificity of the EKG abnormality are used to revise the estimate of disease probability, and so on.  As new information is obtained, the previous probability of disease is used to come up with a new estimate- exactly as is done in an office setting- as new information comes to light, the probability of disease goes either up or down. This approach was used by Diamond and Forrester (2) to calculate the probability of coronary artery disease and has been used many times since then. This same method can help diagnose HCM during screening of athletes.

The prevalence of HCM is well known (3). The generally accepted prevalence is that 1 person out of 500 people (0.2%) in the population will have HCM.  This has recently been revised and the new estimate is 1 person out of 200 people (0.5%) may have HCM.  For the purposes of the screening tool, both numbers are used to provide a range of probabilities. 

A detailed history and physical are the cornerstones of the cardiovascular screening of athletes. Every athlete fills out a standard American Heart Association questionnaire and a physical examination is performed.  For the purpose of diagnosing HCM, two items on the questionnaire are of interest.  A prior history of unexplained syncope may be associated with HCM.  This has been studied and it has been determined that the sensitivity for unexplained syncope in diagnosing HCM is 35% and the specificity is 85% (4). Since HCM is a genetic disease and runs in families, the family history is very important.  A family history of unexplained SCD has a sensitivity of 42% and a specificity of 79% in diagnosing HCM (4).  A family history of HCM carries a sensitivity of 44% and a specificity of 99% (5). Findings on physical examination can also determine the presence of HCM.  The classic murmur of HCM is a harsh systolic murmur that gets louder with Valsalva maneuver. The sensitivity of a systolic murmur, louder with Valsalva, is 65% while the specificity is 96% (4). The history and physical examination may not be able to definitively diagnose HCM (the sensitivities are quite low), but if these factors are present, the probability of HCM increases and additional testing is warranted.

The next test during an athletic screening is the EKG.  While controversial and not performed routinely in all parts of the world, the EKG should be done if one suspects HCM.  Many patients with HCM have abnormal and bizarre EKGs.  An EKG is abnormal if it meets the findings of the 2013 Seattle criteria and the updated 2017 International criteria.  The sensitivity of an abnormal EKG in diagnosing HCM using the Seattle/International criteria is 93% with a specificity of 96% (6).  

Lastly, an echo is often done during screening of athletes.  Usually an echo is performed if there is a reasonable probability that a condition which may cause SCD is present.  An echo is often used to rule in or rule out a diagnosis of HCM.  While the differentiation between HCM and an athlete’s heart on echo can be difficult, at screening one needs to determine if the heart is hypertrophied or not and whether additional testing is necessary.  There are many criteria used to diagnose HCM on echo, but three criteria are the generally accepted starting points in making the diagnosis: interventricular septal wall to posterior wall ratio greater than or equal to 1.3, systolic anterior motion (SAM) of the mitral valve and maximal interventricular septal thickness >1.5 cm (7).  These three parameters are easily obtained on echo during a screening session for athletes; they don’t require additional expertise by the echo tech or echo reader. An interventricular septal wall to posterior wall ratio greater than or equal to 1.3 has a sensitivity of 76% and a specificity of 93% (7). Systolic anterior motion of the mitral valve has a sensitivity of 82% and a specificity of 99% (7). Maximal interventricular septal thickness >1.5 cm has a sensitivity of 87% and a specificity of 97% (8). 

Table of Sensitivities and Specificities in Diagnosing HCM

	Sensitivity	Specificity
Unexplained syncope	0.35	0.82
Family History of unexplained SCD	0.42	0.79
Family History of HCM	0.44	0.99
Systolic murmur increased w/Valsalva	0.65	0.96
Abnormal EKG - Seattle/International Criteria	0.93	0.96
Septal/Posterior wall ratio => 1.3	0.76	0.93
SAM	0.82	0.99
Interventricular septum > 1.5 cm	0.87	0.97

                                                                                                            

How does the Bayes calculator work? Currently, it is a spreadsheet and the relevant factors (ex, family history HCM) are set to a default of 0.  If a factor is positive, then the 0 is replaced by a 1 and a new posttest probability is displayed.

Take for example an athlete whose only positive finding is a prior history of unexplained syncope, the physical is normal and the EKG is normal. In this case, the baseline probability of HCM goes from 0.2% - 0.5% to 0.4% - 1%. This is still quite a low probability and if one is wondering whether to do an echo, it may acceptable to skip additional testing. 

	1/500	1/200
Prevalence of HCM	0.002	0.005
Unexplained syncope	1	1
Family History of unexplained SCD	0	0
Family History of HCM	0	0
Systolic murmur increased w/Valsalva	0	0
Abnormal EKG - Seattle/International Criteria	0	0
Post Test Probability	0.004	0.010

Now if the same athlete has a history of unexplained syncope and an abnormal EKG by Seattle/International criteria, then the probability of HCM goes to 8%- 18%. This is now in an intermediate range and doing an echo would be prudent.

	1/500	1/200
Prevalence of HCM	0.002	0.005
Unexplained syncope	1	1
Family History of unexplained SCD	0	0
Family History of HCM	0	0
Systolic murmur increased w/Valsalva	0	0
Abnormal EKG - Seattle/International Criteria	1	1
Post Test Probability	0.083	0.185

If an echo is done and the interventricular septum is greater than 1.5 cm, the posttest probability goes to 72-87%, all but cinching a diagnosis of HCM.

	1/500	1/200
Prevalence of HCM	0.002	0.005
Unexplained syncope	1	1
Family History of unexplained SCD	0	0
Family History of HCM	0	0
Systolic murmur increased w/Valsalva	0	0
Abnormal EKG - Seattle/International Criteria	1	1
Post Test Probability	0.083	0.185
Echo
Septal/Posterior wall ratio => 1.3	0	0
SAM	0	0
Interventricular septum > 1.5 cm	1	1
Post Test Probability (+ echo)	0.724	0.868
Post Test Probability ( - echo)	0.016	0.040

The calculator may be helpful in another way. For example, take an athlete who has a family history of HCM and an abnormal EKG. The posttest probability is quite high (67-84%). If, however, the athlete has a negative echo, the posttest probability of a negative echo drops to 27 to 48%. While the probability at this time is lower, this athlete should not be ignored, the probability of HCM is still close to 50%. This scenario represents an athlete who should be followed over time and have repeated echoes.  Even though he doesn’t have HCM at present, he is at risk and may develop it in the future. Young athletes with abnormal EKGs and normal echoes may represent an early phase of the disease and it may be evident years later (9). The calculator may help identify these athletes.

Other causes of SCD in athletes are even less prevalent than HCM. In addition, they do not have the same clues on history and physical examination. The EKG can have subtle abnormalities or it can be normal. The echo can be diagnostic, but oftentimes additional testing (stress testing or cardiac MRI for example) is necessary to diagnose one of these conditions. These tests are not part of a screening evaluation for athletes. Take arrhythmogenic right ventricular dysplasia (ARVD) as an example. The prevalence is 1 in 5000 (ten times higher than HCM) (10). Sensitivities and specificities are known for common EKG abnormalities in ARVD (11).  The pretest probability of ARVD is very low due to the low prevalence, about 0.02%. Even if the EKG is abnormal, the posttest probability is only 1.3%, still quite low. The Bayesian approach may not be helpful.

ARVD	1/5000
Prevalence	0.000200
Positive Family History- ARVD in first degree relative	0
Inverted T waves in V1, V2 and V3 or beyond in patient > 14 yrs old, w/o RBBB	1
Epsilon wave in V1, V2, V3, w/o RBBB	1
Post Test Probability	0.013598

Using the Bayes calculator may be helpful in diagnosing HCM during a routine athlete screening and in identifying athletes who need to be followed closely over time.  The tool uses commonly available variables during a typical athlete screening session and takes only a few minutes to use. However, it has not been prospectively validated. 

Steven Georgeson, MD FACC FACP

Medicor Cardiology

Atlantic Medical Group

Bridgewater NJ USA

References:

1.    Circ 1996;94:850-856

2.    NEJM 1979;300:1350-1358

3.    NEJM 2018;379:655-668

4.    Heart 2004;90:570-575

5.    Am J Card 2014;114:1383-1389

6.    Br J Sports Med 2018;52:667-673

7.    JACC Imaging 2008;1:787-800

8.    JACC 1993;22:498-505

9.    NEJM 2008;358:152-161

10.NEJM 2107;376:61-72

11.Circ 2009;120:477-487