Which of the following is an early indicator of heart failure?

Weight gain is an early indicator of heart failure because it often results from fluid retention due to the heart's inability to pump effectively. When the heart fails, it can lead to increased hydrostatic pressure in the blood vessels, causing fluids to leak into surrounding tissues. This fluid accumulation can manifest as weight gain, which may occur over days or even hours, and is often one of the first signs that patients notice. Monitoring weight regularly is crucial for individuals at risk for heart failure as sudden increases can prompt further evaluation and management of their condition.

While shortness of breath during exertion, chest pain, and peripheral edema are significant signs of heart failure, they are typically considered later manifestations as the disease progresses. Shortness of breath often indicates more advanced fluid overload and reduced oxygenation, chest pain may suggest ischemic heart disease, and peripheral edema usually indicates more severe heart failure where the body's compensatory mechanisms have failed.