The Impact of a Short Interval (≤1 Year) between Primary and Reoperative Coronary Artery Bypass Grafting Procedures

Abstract

Reoperative (redo) coronary artery bypass grafting is an efficient treatment for patients with progressive coronary artery disease and those with conduit failure. Previous studies have demonstrated that a short time interval between primary and redo coronary artery bypass grafting is associated with a significantly higher mortality rate. In the present report this particular group have been specifically evaluated. Between 1 January 1990 and 1 October 1994, 383 consecutive patients underwent redo coronary artery bypass grafting. Thirty-three patients (8.6%) were operated on at ≤ 1 year (group I) and 350 patients at > 1 year after the primary bypass (group II). The main indications for redo in group I were graft failure (58%), incomplete revascularization (39%) and progress of disease (3%); respective values in group II were 26%, 15%, and 23%. In addition, 36% of patients in group II had combinations of complications. Patient characteristics did not differ between groups, except a higher incidence of insulin-dependent diabetes in group I ( P < 0.05). There was a higher incidence of left main stem stenosis of >70% in group I ( P< 0.05). Group I patients had a longer aortic cross-clamping time and needed thromboendarterectomy and patching of coronary vessels more often than did those in group II ( P < 0.05). The internal mammary artery had been more frequently used at the primary coronary artery bypass grafting in group I ( P < 0.01). The overall mortality rate was 8.9%; that in group I was 18% and in group II, 8% ( P < 0.05). There was a higher incidence of non-fatal myocardial infarction and a need for prolonged ventilatory support (>24 h) in group I. Other postoperative complications did not differ. Significant risk factors for mortality in group I were preoperative Canadian Cardiovascular Society class ≥3, unstable angina, need for urgent operation and left ventricular ejection fraction <40%, and ≥70% left main stem stenosis. In group II, the risk factors were: unstable angina, urgent operation, left ventricular ejection fraction <40%, internal mammary artery not used at primary coronary artery bypass grafting and the need for coronary thromboendarterectomy. The 3-year survival and cardiac event-free survival did not differ between the groups. This study has confirmed that early redo coronary artery bypass grafting (≤ 1 year from primary bypass) is associated with an increased operative risk.