Abstract

Gated cardiac blood-pool imaging under rest and exercise was used to assess left-ventricular functional reserve in six asymptomatic patients with prior myocarditis and six age matched control subjects. Coronary artery disease was excluded in three of the six patients by coronary arteriography. In the remaining three, coronary artery disease was thought unlikely on the basis of history and the presence, during exercise, of a normal ECG and normal Tl-201 myocardial image. Conventional indices of resting left-ventricular function--including cardiothoracic ratio, echocardiographic left-ventricular diameter, and percentage change in minor diameter--were normal in those with prior myocarditis. The mean resting left-ventricular ejection fraction was also normal by gated blood-pool imaging, and not significantly different from that for control patients: 0.58 +/- 0.05 and 0.65 +/- 0.02, respectively. Three patients with prior myocarditis had resting left-ventricular ejection fractions of less than 0.50. On exercise, the patients with prior myocarditis decreased their mean left-ventricular ejection fraction by an average of 8% compared with an increase of 15% in the control group (p less than 0.01). This study suggests that asymptomatic patients with prior myocarditis have left-ventricular dysfunction that may not be clinically apparent, and suggests the need for further long-term follow-up.