Septal wall thinning and systolic dysfunction in patients with hypertrophic cardiomyopathy caused by a cardiac troponin I gene mutation

Background Lysine 183 deletion in the cardiac troponin I gene is 1 of the mutations that causes hypertrophic cardiomyopathy (HCM). However, the clinical course and determinants of poor prognosis in patients with this mutation have not been well established. Methods and Results We analyzed 10 probands with HCM caused by this mutation and their family members. Forty-six of these 79 subjects were found to be carriers, and 33 were non-carriers. All non-carriers had a percent fractional shortening (%FS) of >25% at all ages. By contrast, 7 of 24 carriers >40 years of age had a %FS of <25%, and no carriers <40 years of age had a %FS of <25%. The change in interventricular septal thickness and the change in %FS were significantly correlated (R = 0.758; P = .0017). Conclusion These results suggest that about 30% of patients with HCM caused by a lysine 183 deletion mutation in the cardiac troponin I gene have systolic dysfunction develop after 40 years of age, and that patients with this mutation whose interventricular septal thickness shows a serial decrease should be followed-up closely for development of systolic dysfunction. (Am Heart J 2002;143:690-5.)