What is the most common first symptom of restrictive cardiomyopathy?

The most common first symptom of restrictive cardiomyopathy is exertion intolerance. This condition is characterized by the heart muscle becoming stiff and less able to relax, which impairs the heart's ability to fill with blood during diastole. As a result, patients often experience symptoms related to heart failure due to decreased cardiac output during exertion.

Exertion intolerance manifests as fatigue, shortness of breath, or decreased exercise capacity. It tends to be one of the earliest indicators of the disease because physical activity demands greater cardiac output, which the stiffened heart cannot adequately provide. As the disease progresses, patients may experience more pronounced symptoms, including fluid retention, but the initial complaint is classically related to exertional limitations. Understanding this characteristic symptom is crucial for early recognition and management of the condition.