RANDOMIZED TRIAL OF NORMOTHERMIC VERSUS HYPOTHERMIC CORONARY-BYPASS SURGERY

Warm heart surgery-37 degrees C cardioplegia with systemic normothermi a-has been introduced as an alternative to conventional hypothermic ca rdiac surgery. A randomised trial comparing warm (W) and cold (C) meth ods was done in 1732 patients undergoing isolated coronary bypass surg ery in three adult cardiac surgery centres at the University of Toront o, Canada. Allocation to W (860 patients) or C (872) was stratified by urgent Versus elective operations and by surgeon. There were no strik ing baseline differences in patients' demographics, angiographic findi ngs, or operative procedures. All but 4.2% of patients initially recei ved antegrade cardioplegia; a further 2.1% switched to retrograde deli very intra-operatively. Crossovers to C occurred in 7.7% of cases eith er due to difficulty in sustaining cardiac arrest or due to coronary f looding. Analysis, however, was on an intention-to-treat basis. The 30 -day all-cause mortality was 2.5& in C patients and 1.4% in the W grou p (p 0.12). There was no difference in non-fatal Q-wave infarction rat es (W 10.1X, C 11.1%), but enzymatic infarction by serial creatine kin ase MB fraction (CK-MB) measurements was reduced (W 12.3% vs C 17.3%, p<0.001) as was the mean area under the CK-MB curve. Postoperative low -output syndrome was less frequent in W patients (6.1% vs 9.3%, p 0.01 ). There were no differences in the rates of stroke, reoperation for b leeding or tamponade, or sternal rewiring/ debridement for dehiscence or infection. Warm heart surgery is a safe and effective alternative t o conventional hypothermic techniques for patients undergoing coronary bypass surgery.