What is the most common cause of right-sided CHF?

The most common cause of right-sided congestive heart failure (CHF) is indeed left-sided CHF. When the left side of the heart fails, it can lead to an increase in pressure in the pulmonary circulation. This pressure overload causes fluid to back up into the lungs, which can eventually elevate the pressure in the right side of the heart as it works to pump against this increased resistance.

As the right ventricle faces additional strain from the elevated pressures in the pulmonary arteries, it may begin to weaken and fail. This condition is referred to as right-sided heart failure, and it often occurs as a result of the sequelae of left-sided failure, making left-sided CHF a common precursor.

In contrast, lung diseases can cause right-sided heart failure through direct effects on the pulmonary vascular system, but they are less common than the transition from left-sided heart failure. Other conditions such as coronary artery disease and cardiomyopathy can contribute to heart failure but do not directly explain the typical pathway leading to isolated right-sided CHF as clearly as left-sided failure does.