What is the most important initial diagnostic study in a patient with suspected HF?
A transthoracic 2 dimensional echocardiogram with Doppler flow studies, because it defines the type and severity of LV impairment. It allows measurement of ejection fraction, ventricular mass, chamber dimensions, and wall motion in addition to eval of valvular, pericardial, and vascular structures. It also allows measurement of flow across the mitral valve, categorizing patients into normal (E>A), delayed relaxation (E<A), and restrictive (E>>A) filling patterns. An abnormal E:A ratio is associated with diastolic HF.