DETECTION OF REGIONAL LEFT-VENTRICULAR ASYNCHRONY IN OBSTRUCTIVE HYPERTROPHIC CARDIOMYOPATHY BY MAGNETIC-RESONANCE-IMAGING

Cine magnetic resonance imaging was used to analyze global and regiona l left ventricular function in seven patients with obstructive hypertr ophic cardiomyopathy (HC) and 10 normal subjects. In patients with HC a 38% higher left ventricular mass index (106.4 +/- 20.2 gm/m(2) vs 77 .0 +/- 16.1 gm/m(2), p < 0.005) associated with a lower end-diastolic volume index (44.9 +/- 8.9 ml/m(2) vs 58.3 +/- 9.0 ml/m(2), p < 0.005) resulted in an 85% higher mass-to-volume ratio (2.4 +/- 0.52 vs 1.3 /- 0.57, p < 0.0005). Stroke volume did not differ significantly, wher eas ejection fraction was higher (80.4% +/- 6.5% vs 65.4% +/- 7.2%, p < 0.0005) in patients with HC. Although early diastolic filling fracti on was smaller in patients with HC (61.0% +/- 22.8% vs 68.4% +/- 14.6% ), the difference did not reach significance because of substantial va riability. In patients with HC (in contrast to normal subjects) the ti me to maximal wall thickening was shorter (p < 0.025) in the hypertrop hied basal region of the ventricle (223 +/-: 42 msec) than in the apic al region (267 +/- 35 msec), reflecting asynchrony between these regio ns. Additionally, in patients with HC the standard deviation of the ti me to maximal wall thickening in the basal region was significantly hi gher when compared with that of normal subjects (40.0 +/- 24 msec vs 1 6.9 +/- 17 msec, p < 0.0005), reflecting asynchrony even within one re gion. Thus magnetic resonance imaging can detect regional left ventric ular asynchrony, an important cause of impaired diastolic function, in patients with HC and normal global systolic function. It might theref ore be of value especially when analysis of left ventricular filling y ields equivocal results.