Abbreviation of systolic time intervals in acute mitral regurgitation: effect of prosthetic mitral valve replacement.

Systolic time intervals were measured in 26 patients with mitral regurgitation (acute in 14 and chronic in 12). In 13 of these patients (7 with acute and 6 with chronic mitral regurgitation) systolic time intervals were also measured after mitral valve replacement. Total electromechanical systole corrected for heart rate (Q-S₂I) was of much shorter duration in the group with acute mitral regurgitation (472 ± 9 msec [mean ± standard error of the mean]) than in the group with chronic mitral regurgitation (516 ± 4.6 msec, P < 0.01). Before operation, the ratio of the preejection period (PEP) to left ventricular ejection time (LVET) and the angiographic ejection fraction did not differ in the groups with acute and chronic mitral regurgitation. The correlation between the $\text{PEP}\text{LVET}$ ratio and ejection fraction was r = ? 0.84, P < 0.01. Two weeks after operation, the $\text{PEP}\text{LVET}$ ratio increased in all patients, but the increase was greater in those with lower preoperative values for this ratio. The mechanism of the early postoperative increase in the $\text{PEP}\text{LVET}$ ratio is not clear, but serial studies performed over 6 months showed a return toward the preoperative value. It is concluded that preoperative systolic time intervals are useful for assessing left ventricular performance in all types of mitral regurgitation, but are especially useful for distinguishing between the acute and chronic varieties.