SERIAL CHANGES IN LEFT-VENTRICULAR FUNCTION AFTER CORONARY-ARTERY BYPASS - IMPLICATIONS IN VIABILITY ASSESSMENT

Improvement in left ventricular (LV) performance after coronary artery bypass surgery remains the gold standard in myocardial viability asse ssment. The time-related changes, however, are not well known. This st udy examined the LV ejection fraction (EF) by gated blood pool imaging early (6 +/- 4 days) and late (62 +/- 24 days) after surgery in patie nts with normal preoperative EF (group 1, n = 12) and those with LV dy sfunction (group 2, n = 15). There were no changes in the clinical sta tus between the early and late studies, and all patients had normal si nus rhythm. Group 1 had no significant change in EF (preoperatively 62 %, early postoperatively 64%, late postoperatively 63%; p = NS). In gr oup 2, EF was 26% +/- 8% preoperatively; 30% +/- 10% early postoperati vely; and 34% +/- 8% late postoperatively (p < 0.05). Postoperatively there was greater than or equal to 5% improvement in EF in 4 patients early and 11 patients late (p < 0.05). Patients who showed early impro vement continued to do so in the late study but, additionally, 7 patie nts showed improvement only in the late study. Thus the timing of EF m easurement after surgery is important in patients with LV dysfunction but not in patients with normal LV function. Early assessment may unde restimate the prevalence and degree of recovery.