Heart Failure In HCM
Overview: Heart failure (HF) means that the heart cannot keep up with its workload; it does not pump as well as it should.
Heart failure is a term that can be confusing. It does not mean that the heart stops (that is called cardiac arrest)!
By definition, HCM is a form of heart failure: the heart does not work normally, and the stiffness of the left ventricle means that the output of blood is generally not enough. But HF is often used to mean something a bit narrower: the heart does not pump adequately, and as a result, fluid accumulates in the body.
There are different forms and different degrees of heart failure. HF can lead to symptoms of shortness of breath, fatigue or light-headedness. While it can be a serious problem, many people live long lives with HF.
One way of understanding heart failure is with the ejection fraction (EF). The EF is a fraction,
EF = amount of blood pumped out of the LV/amount of blood in the LV.
EF is normally between about 55% and 70%.
The ejection fraction is useful, but it can be misleading too. To see why, think of a heart with almost no cavity in the left ventricle - so the denominator is very small. The EF might be normal or even high, but that does not mean that much blood is being pumped out! Knowing your EF is important, but a cardiologist would want to know much more before saying anything about how your heart is.
Major forms of heart failure
Another reason heart failure can seem confusing is that there is more than one way the heart can fail to pump adequately. A moment's thought suggests that it can fail to fill adequately. It can also fail to squeeze blood out adequately. Put differently, the amount of blood being pumped out to your body could be small because the numerator in EF could be very small (the left ventricle isn't squeezing hard enough), or the denominator is very small (the left ventricle isn't filling well, or is too small), It is also possible - but not common - for the heart to fail in both ways.
Systolic heart failure:
Systolic heart failure is what many doctors mean by HF. It occurs when the left ventricle (LV) does not squeeze hard enough to pump blood adequately out to the body. In other words, the numerator in EF is low. This is the most common form of HF in the population as a whole, but is uncommon in HCM.
What happens to the heart?
Systolic heart failure typically affects the left ventricle. Systole is the pumping phase of a heart beat, or the "squeeze." In systolic HF, the left ventricle does not squeeze forcefully enough during systole. Over time, the LV can enlarge and the walls can thin.
Tests may show a low ejection fraction (EF). Doctors sometimes call systolic HF "heart failure with reduced ejection fraction."
Diastolic heart failure:
Diastolic heart failure (or diastolic dysfunction) occurs when the left ventricle does not fill adequately during the diastolic (filling) phase of the heartbeat. Diastolic HF - because of the stiffness of the LV and because the left ventricular cavity is reduced in size by the hypertrophy in the walls - is typical of HCM.
What happens to the heart?
Diastole is the filling phase of the heartbeat. In diastolic dysfunction or HF, the reduced amount of blood coming out of the heart is because the ventricle does not fill well enough. In other words, the denominator in the EF equation is large. This means that EF may be normal or even high. A high EF does not mean that the heart is doing well. Diastolic HF is also called "heart failure with preserved ejection fraction." If diastolic dysfunction is severe enough, fluids can back up, typically into the lungs.
What about congestive heart failure (CHF)?
CHF means that fluid is accumulating in the body because of HF. Both systolic and diastolic HF can cause this. Congestive heart failure is really a description of symptoms and not a distinct type of a disease.
If you have fluid accumulation (which you might see as swollen ankles, coughing, and shortness of breath), you need medical treatment to help rid yourself of the extra fluids. If you notice a sudden weight gain (like 3 lbs (1 kg) or more in a day, or 5 lbs (2 kg) in a week), you need attention even if you do not have other symptoms.
Treatment of heart failure
Managing heart failure is a major sub-specialty of cardiology, so we won't claim to be complete here! Acute heart failure is typically treated with diuretics (to help your kidneys flush out the extra fluid). Graduated compression socks are also frequently used to help push blood up through the veins in your legs. Doctors frequently recommend staying off your feet when possible, and elevating your feet above your heart. Often, fluid intake needs to be limited. In HCM patients this can be a delicate balancing act, because dehydration makes our hearts function more poorly. Your doctor will probably prescribe drugs - beta blockers or calcium channel blockers - to slow your heart rate, improving the left ventricle's ability to fill. They may prescribe additional drugs as well.
What happens if my heart failure is uncontrollable?
When heart failure becomes severe, causing congestive heart failure, more aggressive medications may be used. There are specialized devices for patients with advanced heart failure, but these are often not usable in HCM patients. For example, a ventricular assist device (VAD) is a pump attached to your heart to help the weakened ventricle pump blood. However, there is frequently not enough room in HCM patients' chests for VADs to be used. If all other options fail and HF is quite severe, heart transplantation may be considered. It is VERY important to remember that fewer than 5% of those diagnosed with HCM will ever need to consider this option.
Maron, B. J., Rowin, E. J., Udelson, J. E., & Maron, M. S. (2018, May 6). Clinical Spectrum and Management of Heart Failure in Hypertrophic Cardiomyopathy. Journal of the American College of Cardiology. Retrieved January 18, 2021, from https://www.jacc.org/doi/full/10.1016/j.jchf.2017.09.011?_ga=2.180702439.1540755187.1611016030-1659945833.1611016030