The prognostic importance of left ventricular outflow obstruction in hypertrophic cardiomyopathy varies in relation to the severity of symptoms

In patients with HCM, the prognostic importance of LV outflow obstruction varies in relation to the severity of symptoms. In patients with mild or no symptoms, obstruction is an important predictor of cardiovascular death. After development of severe symptoms, NYHA functional class becomes the dominant marker of prognosis independently of the presence of an outflow gradient.