Michael A. Borger

Stroke during coronary bypass surgery: principal role of cerebral macroemboli

OBJECTIVE The purpose of this study was to gain insight into the etiology of stroke during coronary bypass surgery. METHODS Retrospective review of prospectively gathered data on 6682 consecutive coronary bypass patients. Patients undergoing simultaneous procedures, including carotid endarterectomy, were excluded. We performed a systematic chart review of all patients who suffered a perioperative stroke. Predictors of stroke were determined with stepwise logistic regression analysis. RESULTS The prevalence of stroke was 1.5% (n=98). Stroke patients had significantly increased intensive care unit and hospital length of stays, as well as increased mortality when compared to patients without stroke (all P< 0.001). Independent predictors of stroke were (in decreasing order of magnitude): age >70 years, left ventricular ejection fraction <40%, previous stroke or transient ischemic attack, normothermic cardiopulmonary bypass, diabetes, and peripheral vascular disease. Chart review revealed that the probable cause of stroke was macroemboli, likely from ascending aorta atherosclerosis, in 37% of patients and unknown in 38% of patients. Computerized tomography (CT) scans were obtained in 79 patients (81%). Lesions detected by CT were consistent with a macroembolic etiology: nearly all lesions were ischemic in nature and located in the distribution of major cerebral arteries, particularly the middle cerebral artery. CONCLUSIONS Stroke is a devastating complication of coronary bypass surgery. Our multivariable risk factors for stroke, chart review, and CT findings all suggest that macroemboli, presumably from the ascending aorta, are the predominant cause of stroke during coronary bypass surgery. Future studies should be directed at minimizing the risk of embolization during cardiac surgery.

Mid-term outcomes of off-pump versus on-pump coronary artery bypass graft surgery

OBJECTIVE To evaluate survival and readmissions to hospital for cardiac events or coronary revascularization (REVASC) in patients having off-pump (OPCAB) versus conventional on-pump (CCAB) coronary artery bypass graft surgery (CABG). METHODS Of 11,368 consecutive patients undergoing isolated CABG between 1996 and 2002, 514 had OPCAB surgery. Using propensity scores, 503 CCAB patients were randomly matched to 503 OPCAB patients. RESULTS There were no clinical or statistical differences between the two groups for any prognostic variable. However, OPCAB patients received significantly fewer distal anastomoses than the CCAB group (2.6+/-1.0 versus 3.1+/-1.0; P<0.001). There was no difference in operative mortality (OPCAB 1.0%, CCAB 1.4%; P=0.6), but the OPCAB group had significantly fewer operative strokes (0.2% versus 1.8%; P=0.01). Follow-up was 99.7% complete at 2.2+/-1.2 years (range 0 to 6 years). Twice as many OPCAB patients (n=24) required REVASC compared with the CCAB (n=11) group. The following five-year actuarial outcomes are presented for CCAB and OPCAB, respectively: survival: 77+/-6%, 76+/-8%, P=0.8; freedom from REVASC: 95+/-3%, 92+/-2%, P=0.02; and cardiac event-free survival: 76+/-5%, 62+/-8%; P=0.05. Cox regression revealed that OPCAB was a significant independent predictor of poorer freedom from REVASC (RR 2.2, 95% CI 1.0 to 4.6; P=0.04) and cardiac event-free survival (RR 1.6, 95%CI 1.1 to 2.2; P=0.02). CONCLUSIONS The use of OPCAB remains controversial. These results, from this early experience, suggest that despite improved hospital outcomes, the lesser degree of REVASC raises concerns about the need for repeat revascularization in the OPCAB group.

Preventing Stroke During Coronary Bypass: Are We Focusing on the Wrong Culprit?

Ozatik et al have presented their results on 8547 consecutive coronary artery bypass grafting (CABG) patients operated on over a nine year period. The authors are to be congratulated for achieving excellent results, with only 0.9% of patients suffering a perioperative stroke. The authors identified elderly age, left main coronary disease, peripheral vascular disease and early date of operation as independent predictors of stroke. They conclude that preoperative carotid Doppler and intraoperative epiaortic scanning may lower the risk of stroke, since these measures were routinely used in the more recent cohort of patients. The main purposes of this paper are: (1) to identify risk factors for stroke in patients undergoing CABG surgery, and (2) to propose preventative measures for this devastating complication. The first objective has been addressed repeatedly in the cardiac surgery literature, with most studies identifying risk factors similar to those observed by Ozatik et al. Frequently cited independent predictors include age, previous stroke or TIA, carotid stenosis, peripheral vascular disease, left ventricular dysfunction, left main coronary disease, renal failure, hypertension and diabetes. However, it is unlikely that any of these factors, with the possible exception of carotid disease, play a direct role in the pathogenesis of perioperative stroke. An increasing amount of evidence in the literature points to ascending aortic atherosclerosis as the principal culprit in the etiology of post-CABG stroke.1 Studies that include this variable in their analysis invariably report the largest odds ratio for ascending aorta atherosclerosis.2 Unfortunately, most cardiac surgery databases, like the one used in the current study, do not prospectively record ascending aorta disease. The result is the identification of a group of risk factors that are merely surrogate markers for ascending aortic atherosclerosis. Future studies on the predictors of stroke during cardiac surgery should routinely include ascending aortic disease as one of the study variables. The second objective of the current study was to propose methods of decreasing the incidence of postCABG stroke. It is only logical that if ascending aorta atherosclerosis is the principal cause of stroke, then prevention should focus on methods of decreasing em-

Infective Endocarditis of the Tricuspid Valve

Abstract  Infective endocarditis (IE) usually involves the left‐sided valves, and IE involving the tricuspid valve (TV) is rare, often developing in intravenous drug users (IDU). We present a case of a 32‐year‐old male, an intravenous drug abuser (IDA), who presented with nonspecific septic symptoms, and was treated with TV conserving surgery. Pathological examination confirmed tissue destruction, friable thrombotic vegetations, and microorganisms in the leaflet tissue.