Which clinical sign is most indicative of left heart failure?

Dyspnea on exertion is most indicative of left heart failure because it reflects the impaired ability of the left ventricle to effectively pump blood, leading to pulmonary congestion. In left heart failure, the heart struggles to maintain adequate cardiac output, which can cause blood to back up into the pulmonary circulation. This results in fluid accumulation in the lungs, a condition known as pulmonary congestion or pulmonary edema. As a person exerts themselves, the increased demand for oxygen and blood flow exceeds the compromised output of the left heart, leading to shortness of breath or dyspnea.

While other clinical signs may appear in cases of heart failure, they are not as specifically indicative of left heart failure. An irregular pulse may suggest arrhythmias that can occur due to various heart conditions, not exclusively linked to left heart failure. Severe peripheral edema is more commonly associated with right heart failure, where systemic venous congestion occurs. Jugular venous distention generally indicates right heart dysfunction or fluid overload, rather than being a primary indicator of left-sided heart failure.