HFrEF

Think of a once-strong dam pump whose blades have gone slack: with each cycle it only manages to push out a small fraction of the water it holds. HFrEF is heart failure where the main pumping chamber, the left ventricle, contracts weakly, so each beat ejects a smaller-than-normal share of its contents.

Formally, HFrEF is heart failure in which the left ventricular ejection fraction is 40 percent or lower (a healthy heart ejects roughly 55 to 70 percent each beat). The underlying problem is impaired contraction — the muscle has been damaged or weakened, most often by a previous heart attack, but also by dilated cardiomyopathy, viral myocarditis, alcohol, chemotherapy, or chronic uncontrolled high blood pressure. The ventricle typically enlarges and changes shape, a process called remodeling.

HFrEF is the form of heart failure with the strongest evidence base for medication. A combination of drug classes — including beta-blockers, ACE inhibitors or sacubitril-valsartan, mineralocorticoid antagonists, and SGLT2 inhibitors — has been shown to reduce hospitalizations and prolong life. Devices such as defibrillators and resynchronization therapy help selected patients.