NEW SUBTYPE OF APICAL HYPERTROPHIC CARDIOMYOPATHY IDENTIFIED WITH NUCLEAR-MAGNETIC-RESONANCE IMAGING AS AN UNDERLYING CAUSE OF MARKEDLY INVERTED-T WAVES

Objectives. The aim of this study was to elucidate the clinical import ance of a new subtype of apical hypertrophic cardiomyopathy that could not be diagnosed with the classical diagnostic criteria. Background. Apical hypertrophic cardiomyopathy is recognized by a characteristic s pade-shaped intraventricular cavity on the end-diastolic left ventricu logram in the right anterior oblique projection, often associated with giant negative T waves [negativity greater-than-or-equal-to 1.0 mV (1 0 mm)]. As an underlying cause of giant negative T waves, an additiona l new subtype of apical hypertrophic cardiomyopathy has been identifie d. Methods. In 40 patients with inverted T waves (negativity greater-t han-or-equal-to 0.5 mV), including 26 patients with giant negative T w aves, nuclear magnetic resonance (NMR) long-axis images corresponding to the left ventriculogram in the right anterior oblique projection an d short-axis images at various levels, including the apical level, wer e obtained to define the site of hypertrophied myocardium. Results. Lo ng-axis images indicated a spadelike configuration in 17 patients, whe reas this diagnostic configuration was not present in the other 23 pat ients. Nine of these 23 patients had significantly hypertrophied myoca rdium at the basal level. In the 14 remaining patients, short-axis ima ges indicated no hypertrophy at the basal level and proved that the ar ea of hypertrophied myocardium was confined to a narrow region of the septum or the anterior or lateral wall at the apical level (nonspade a pical hypertrophic cardiomyopathy). The hypertrophied myocardium of th e nonspade type was so narrowly confined that the mass did not form a spadelike configuration or could not be detected on the long-axis imag e. Conclusions. Nonspade apical hypertrophic cardiomyopathy was newly identified on NMR short-axis images, and this could be an additional, important underlying cause of moderately to severely inverted T waves.