SOLITARY PAPILLARY-MUSCLE HYPERTROPHY AS A POSSIBLE FORM OF HYPERTROPHIC CARDIOMYOPATHY

Patients can present with hypertrophied papillary muscles in the left ventricle, even without hypertrophy in other segments, and they have e lectrocardiographic (ECG) abnormalities suggestive of hypertrophic car diomyopathy (HCM). This study was performed to evaluate whether the so litary papillary muscle hypertrophy was related to HCM. By analyzing 6 731 echocardiographic studies between 1990 and 1994, the incidence of patients with papillary muscle hypertrophy was retrospectively examine d, as well as the ECG features and family history related to HCM in th ese patients. After the normal size of the anterolateral and posterome dial papillary muscles was obtained from echocardiographic studies in 40 healthy subjects (0.7+/-0.2 cm for each of the vertical and horizon tal axis), papillary muscle hypertrophy was defined as follows: either the vertical or horizontal diameter of at least one of the 2 papillar y muscles was more than 1.1 cm (mean+2SD in the normal subjects). Usin g this definition, 29 patients with papillary muscle hypertrophy were identified, of whom 14 (48%) showed high voltage QRS complexes, 10 (34 %) showed T wave inversion, and 6 (21%) showed abnormal Q waves. Ten p atients (34%) had a family history of HCM. In 2 patients that were fol lowed for 18 and 11 years, respectively, the voltages of the QRS compl exes and inverted T waves progressed with the hypertrophy of the papil lary muscle. These findings suggest that solitary papillary muscle hyp ertrophy is related to HCM and that papillary muscle hypertrophy is a newly identified subtype of or an early form of HCM.