Significance of Maximal and Regional Left Ventricular Wall Thickness in Association With Arrhythmic Events in Patients With Hypertrophic Cardiomyopathy

Background: Increased maximal left ventricular wall thickness (LVWT; >30mm) is a marker of risk for sudden cardiac death in hypertrophic cardiomyopathy (HCM). Patients with mild left ventricular hypertrophy (LVH) are not free of events. Regional heterogeneity of LVH may contribute to arrhythmic vulnerability. Methods and Results: 157 HCM patients underwent assessment of maximal and regional LVWT by 2-dimensional echocardiography, and arrhythmic burden in a follow-up of a median 3.7 years. 45 patients with ventricular arrhythmic events (VAEs+ group) had larger maximal LVWT and regional LVWTs (basal anterior-B12 and equatorial inferior-EQ6 segments, P=0.05). Maximal LVWT and B12 above a cut-off value of 15mm were associated with a significant 4.5-fold (95% confidence interval (CI) 1.1-18.8, P=0.04), 3.2-fold (95%CI 1.5-6.7, P<0.002), and EQ6 above 19mm with 5.9-fold (95%CI 2.0-16.9, P<0.001) increased the relative risk of VAEs. Multivariate analysis identified the 2 regional measures as the only predictors, independently associated with arrhythmic risk. Conclusions: Non-invasive imaging measures, such as LVWT, do have a role in identifying the patients at risk of VAEs. In addition to maximal LVWT, the key regional LVWTs provide complementary information of incremental value to the conventional risk stratification model. (Circ J 2010; 74: 531-537)