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.