According to a study published online by JAMA Cardiology, we need to step up our efforts to diagnose and prevent heart disease—still the leading cause of death in the United States. That’s because the notable success we had in decreasing heart disease mortality during the first decade of the 21st century has slowed significantly since 2011.
The researchers found that from 2000 to 2011, heart disease mortality declined at a much greater rate than cancer mortality. It even appeared that cancer would soon—by perhaps 2013—be the leading cause of death in this country instead of heart disease. The rate of decline of cardiovascular deaths, however, slowed substantially after 2011, leaving heart disease to remain as the country’s number one killer.
The Most Important Heart Tests for Those Being Evaluated for Heart Disease
To be sure, there are a number of good cardiac screening tests that should be included in any comprehensive preventive and diagnostic cardiac assessment. From all the options available in the massive cardiologist toolbox to assess basic heart function, these are the tests I recommend:
- Electrocardiogram (EKG)
- Echocardiogram
- Exercise/Nuclear Stress Test
- Holter Monitoring
- BNP Test
Electrocardiogram (EKG)
An electrocardiogram or EKG (kardio in German, hence the “EKG” shorthand) is a cardiac screening test that should be done on everyone on their first visit to a cardiologist. An EKG establishes baseline information about the structure of your heart, its electrical conduction patterns, and possible arrhythmias. The “12 lead” EKG measures the electric potential of your heart from 12 different directions. A resting EKG gives us information about the heart's conduction system, including current baseline heart rate and rhythm, and possible heart blocks.
Voltage measurements (signal strength) indicate relative chamber sizes. An EKG also shows things like heart position and signs of possible ischemia (poor oxygen delivery). A record of your EKG when you are healthy is a good baseline for comparison, but resting EKGs have limitations. We can miss problems that might be more evident when your heart is beating faster—hence the need for further testing when your heart rate is elevated during exercise (see Exercise/Nuclear Stress Test below).
Echocardiogram
An echocardiogram or “echo” is a noninvasive ultrasound cardiac screening test that records specific geographical areas of the beating heart, which reveals blood flow patterns and allows us to measure size and wall thickness of the heart's chambers. We can get a good sense of where valves may be too loose and leaky, or too tight and restrictive. In addition, an echo can detect possible enlargement of the heart as well as potential presence of fluid around the heart.
Your echocardiogram results are replayed on a video for a specially trained physician to review and interpret. Still images are then printed in the report. I use the echo to get a dynamic picture of how the heart is functioning as a pump. It also provides information on ejection fraction, which is the percentage of blood that is moving out of your heart on each heartbeat and an overall indicator of heart health.
With a stress echocardiogram, the images are taken at rest and then compared to images taken immediately after exercise. In short, this test combines the diagnostic benefits of real-time ultrasound images and the exercise stress test. Blood flow to specific regions of the heart muscle can be inferred from how well the heart wall is moving in that area.
Exercise/Nuclear Stress Test
An exercise stress heart test (abbreviated GXT for the graded exercise test, or ETT for the exercise treadmill test) is ordered to assess how your heart is functioning when heart rate and blood pressure are increased during physical exertion.
The exercise stress test affords us more information than we can get with the resting EKG. If coronary arteries are blocked, then giving the heart a little work to do may reveal any potential problems. Most of you are probably familiar with the image of a person walking on a treadmill, hooked up to an EKG, but a stationary bicycle may also be employed for those who have difficulty walking.
When you have a nuclear stress test—which is the “Cadillac” of stress tests and the type I highly recommend for anyone experiencing symptoms of heart disease—an intravenous catheter is inserted and nuclear material (like Cardiolite, thallium) is injected when the heart is at peak exercise. After a few minutes of recovery time lying on a table, imaging is performed for up to 30 minutes. Medication may also be administered in the IV that will increase heart rate in place of exercise for those who cannot exert themselves physically. A positive finding indicates that blood flow is restricted in one or more of the various regions of the heart.
Holter Monitoring
A Holter monitor is usually worn for 24 hours and records every heartbeat for that time period. Electrodes are placed on the chest, and a recorder is worn on a shoulder strap or belt. I order this test to identify cardiac arrhythmias, and to monitor how well medication is working to minimize them. Sometimes we see signs of ischemia on Holter, and most Holter monitor computer analysis programs also measure heart rate variability (HRV).
Your heart isn't a machine that simply beats at a fixed rate at all times, as you may well know. It varies from moment to moment with activity, emotions, and so on. HRV is related to your autonomic nervous system function and is another way of quantifying factors related to psychological distress. The more your heart rate fluctuates, the lower your risk of sudden death. According to statistics that have been gathered, poor HRV is a definite risk factor for heart disease.
BNP Test
In some cases, breathing difficulties can be a symptom of a heart problem. For anyone experiencing problematic breathing, I recommend a relatively new blood and heart test that can identify a unique peptide in your bloodstream to determine if your shortness of breath is due to a failing heart.
The BNP test (which, in all likelihood, 50 percent of today‘s physicians aren't even aware of) measures the level of B-type natriuretic peptide (BNP) in your blood. When it is elevated beyond ideal levels, which for males is lower than 33 pg/mL and for females is lower than 50 pg/mL, we know your heart is “on fire” with inflammation and your shortness of breath could be due to a heart problem. The higher the BNP, the more advanced the heart failure.
The B-type natriuretic peptide is synthesized almost exclusively in the heart ventricles—and primarily in the left—and is an absolute marker for cardiac dysfunction at certain levels. Its level correlates with the severity of symptomatic congestive heart failure (CHF). As stated above, the higher the BNP, the more likely the problem is CHF, and the more pronounced shortness of breath will be. So, consider the BNP test the quickest and most conclusive way to determine if the cause of your shortness of breath is heart-related.
