Original article: cardiovascular
Conversion in Off-Pump coronary artery bypass grafting: an analysis of predictors and outcomes

Presented at the Forty-ninth Annual Meeting of the Southern Thoracic Surgical Association, Miami Beach, FL, Nov 7–9, 2002.
https://doi.org/10.1016/S0003-4975(03)00747-1Get rights and content

Abstract

Background

The incidence, predictive factors, and outcomes related to conversion from off-pump coronary artery bypass (OPCAB) to on-pump coronary artery bypass grafting (ONCAB) have not been well defined. We sought to determine the incidence of conversion, predictive factors, and any associated adverse consequences.

Methods

From January 2000 through June 2002, 1,644 patients underwent nonemergent OPCAB with 61 patients requiring conversion from OPCAB to ONCAB. These groups were retrospectively compared by univariate and multivariate regression analysis. The converted group was then computer matched 1:3, to a cohort of ONCAB patients to determine differences in outcomes.

Results

The overall conversion rate was 3.71%. Converted patients compared with a computer-matched ONCAB patients had a higher incidence of operative mortality (18.0% versus 2.7%, p < 0.001). Urgently converted patients had a higher incidence of postoperative cardiac arrest (25% versus 1.1%, p < 0.001), multisystem organ failure (10.7% versus 0.6%, p < 0.001), vascular complications (7.1% versus 1.1%, p = 0.03), and perioperative myocardial infarction (10.7% versus 1.1%, p = 0.02). Predictive factors for conversion were surgeon early in OPCAB experience (odds ratio [OR] 4.4), previous CABG (OR 2.8), and congestive heart failure (OR 2.0). The need for urgent-emergent conversion was highly predictive for operative mortality (OR 7.3) compared with elective conversion.

Conclusions

Patients undergoing urgent-emergent but not elective conversion from OPCAB to ONCAB had a significantly higher risk of mortality and morbidity compared with patients whose procedure was initially ONCAB. Variables predictive of conversion included previous CABG, congestive heart failure, and surgeons early in OPCAB experience.

Section snippets

Patients

Data on a total of 4,689 patients were exported from our Society of Thoracic Surgeons (STS) approved database. These data represented the population of all isolated CABG patients operated on by our group of 22 surgeons from January 1, 2000, to June 30, 2002. Patients whose status was listed as “emergent” or “salvage”, who were in cardiogenic shock, or who were being resuscitated were not included in the study, reasoning that they could only be done on-pump. This excluded a total of 151 patients

Results

The overall conversion rate was 3.71% but the rate varied between groups. Surgeons with a high prior volume of OPCAB cases had a rate of 1.85%, which was statistically lower than the rate for low-volume surgeons (7.13%, p < 0.001) or that recorded for moderate-volume surgeons (4.3%, p = 0.02; Table 1).

Overall, patients converted to ONCAB had a significantly higher mortality rate than computer-matched patients whose procedure was initiated as ONCAB (18% versus 2.7%, p < 0.001). Mortality rates

Comment

Several other studies have addressed the incidence of mortality among converted patients, usually comparing the converted patients with patients who were not converted 5, 6, 7, 8, 9. We sought to determine whether patients started off-pump and converted to on-pump fared less well than if their procedure had been initiated as on- pump. For this reason we compared our converted patients with a computer-derived comparable cohort of patients whose procedure was initiated as ONCAB and who had not

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