Off-Pump CABG Increased Stay and Costs, But Not Survival

SAN FRANCISCO — Off-pump coronary artery bypass grafting was associated with greater costs and length of hospitalization and no difference in the risks of death or stroke, compared with conventional on-pump procedures in a review of 63,061 cases.

The findings are sure to fuel the controversy over which type of coronary artery bypass grafting (CABG) is better—the conventional on-pump (using cardiopulmonary bypass) approach or the more recent off-pump CABG. Some previous studies have shown improved outcomes with off-pump CABG, whereas others have shown worse outcomes.

In the current study, 14,392 patients who underwent CABG without cardiopulmonary bypass pumps averaged 10.2 days in the hospital, compared with 9.9 days in 48,669 patients who had on-pump CABG, a statistically significant difference. After a multivariable logistic regression analysis, off-pump CABG was associated with an extra 0.6 days in the hospital and $1,497 in higher costs, Dr. Danny Chu and his associates reported at the annual meeting of the Society of Thoracic Surgeons.

In-hospital death rates—the primary outcome in the analysis—were about 3% in each group. The incidence of postoperative stroke was about 2% in each group. These rates did not differ significantly between groups.

“Off-pump coronary artery bypass should be an alternative to, not a replacement for, the traditional on-pump CABG,” said Dr. Chu of Baylor College of Medicine, Houston. “We do not believe that performing off-pump CABG on all patients is justifiable.”

Dr. Chu and his associates had no potential conflicts of interest.

The study analyzed data on all U.S. patients undergoing isolated CABG and no concomitant cardiac operations in 2004, using records from the nonvoluntary Nationwide Inpatient Sample (NIS) database maintained by the Agency for Healthcare Research and Quality.

Several preoperative characteristics differed significantly between groups. The off-pump patients averaged a year younger in age than on-pump patients (65 vs. 66 years) and were more likely to be female (31% vs. 29%) and to be emergency cases (29% vs. 25%).

The analysis stratified patients for risk using the Deyo Comorbidity Index, a modification of the validated Charlson Comorbidity Index.

Commenting on the study after Dr. Chu's presentation, Dr. John D. Puskas criticized the investigators' use of an administrative database like the NIS for the purpose of clinical outcomes analysis. The study's conclusions “cannot be justified,” said Dr. Puskas, chief of cardiac surgery at Emory Crawford Long Hospital, Atlanta.

Dr. Puskas is a consultant to, and has received research funds from, Medtronic Inc. and Marquet Medical Systems, which make devices used in CABG (both on- and off-pump). He also has received royalties from coronary instruments marketed by Scanlan International Inc.

Dr. Puskas also was the primary investigator in a review of records on 42,477 consecutive, nonemergency, isolated CABG surgeries, using data from the Society of Thoracic Surgeons National Cardiac Adult Database. His study concluded that off-pump CABG was associated with a 17% lower risk of death, a 35% lower risk of stroke, a 33% lower risk of MI, and a 29% lower risk of major adverse cardiac events compared with on-pump CABG, all significant differences (Ann. Thorac. Surg. 2007;84:1447-56).

“These are very tight data, and they are compelling. This is the most sophisticated and complete risk-adjusted assessment possible, with a very vigorous database,” he said.

A separate recent analysis of the NIS database that analyzed CABG outcomes based on patients' differing coronary anatomy found lower risks for death, MI, stroke, or major adverse cardiac events with off-pump CABG than with on-pump, he added.

'Off-pump coronary artery bypass should be an alternative to, not a replacement for, the traditional on-pump CABG.' DR. CHU