What is the primary symptom of left-sided heart failure?

The primary symptom of left-sided heart failure is pulmonary congestion and edema, which occurs due to the backup of blood into the lungs when the left ventricle cannot effectively pump blood out into the circulation. As a result, fluid accumulates in the lung alveoli, leading to symptoms such as shortness of breath, coughing, and difficulty breathing, especially when lying down. This fluid buildup in the lungs creates the characteristic congestive symptoms associated with left-sided heart failure.

Other symptoms like peripheral edema, which is more commonly associated with right-sided heart failure, may also occur but are not the primary indicators. Syncope can happen due to decreased cardiac output but is not directly related to left-sided heart failure symptoms. Chest pain may result from various conditions, including myocardial ischemia, but isn't a primary symptom of left-sided heart failure itself. This makes pulmonary congestion and edema a clear marker of the left-sided heart failure condition.