The effect of left ventricular outflow tract obstruction (LVOTO) at rest on the 
incidence of sudden death (SD) in patients with hypertrophic cardiomyopathy is 
rather conflicting. The aim of this study was the evaluation of LVOTO at rest as 
a new potential risk factor for SD in hypertrophic cardiomyopathy. A total of 
166 patients (112 men, 51.8 +/- 15.6 years) were studied; 50 patients (30.1%) 
had peak instantaneous LVOTO gradients of > or = 30 mm Hg at rest. During the 
follow-up period (median 32.4 months, range 1 to 209), 13 patients either died 
suddenly, or had cardiac arrest, documented sustained ventricular tachycardia, 
or implantable cardioverter defibrillator discharge. The cumulative event-free 
survival rate was 92% in patients with LVOTO, and 92% in patients without 
obstruction (p = NS). LVOTO at rest was associated with a particularly low 
positive predictive value for SD (8%), although a high negative predictive value 
(92%) was recorded. Patients having syncope or presenting with a maximum wall 
thickness > or =3 cm in echocardiography were more sensitive to SD emergence 
because they had a 13.07 (95% confidence interval 4.00 to 46.95, p <0.0001) and 
a 10.07 (95% confidence interval 2.92 to 34.79, p = 0.003) greater relative 
risk, respectively. In conclusion, our cohort study results do not support LVOTO 
as an independent risk factor for SD in patients with hypertrophic 
cardiomyopathy.