Which diagnostic test provides the most accurate assessment for hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disorder characterized by asymmetric septal hypertrophy, diastolic dysfunction, and dynamic left ventricular outflow tract obstruction. It increases risk of ventricular arrhythmias, syncope, and sudden cardiac death, especially during exertion. Rationale: A. CT scan of the thorax may visualize cardiac structures but is not the primary diagnostic tool for HCM. It lacks functional assessment of blood flow dynamics and valvular obstruction. This does not provide detailed evaluation of myocardial hypertrophy severity. B. Electrocardiogram may show left ventricular hypertrophy or repolarization abnormalities but is not definitive. It provides electrical activity data without structural or functional assessment. This does not accurately measure septal thickness or obstruction. C. Chest X-ray may reveal cardiomegaly in advanced disease but is nonspecific. It cannot assess myocardial structure or functional impairment. This does not evaluate left ventricular outflow tract obstruction. D. Echocardiogram with Doppler imaging is the gold standard for diagnosing hypertrophic cardiomyopathy. It visualizes septal hypertrophy, assesses ventricular function, and measures outflow gradients. This directly evaluates structural and hemodynamic abnormalities.