 Annual mortality from SCA has been estimated at approximately 3. As a significant number of these deaths are sudden, a cardiac cause has been suspected. However, no cardiac mechanism of sudden death SD has been clearly identified. Recently, it has been demonstrated that SCA patients with pulmonary hypertension PAH have a higher incidence of SD than those with normal pulmonary pressures. In many patients, PAH occurs in association with elevated pulmonary arterial wedge pressures and normal pulmonary arterial resistance, suggesting that the PAH develops as the result of left ventricular LV abnormalities. Furthermore, in other conditions in which PAH develops, SD occurs only at pressures considerably higher than those observed in SCA. These factors suggest that PAH in SCA is a surrogate marker for, rather than the cause of SD. Rather, an SCA cardiomyopathic process may provide a unifying mechanism that associates moderate degrees of PAH and high risk of SD from cardiac causes. 