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Statins and Bypass Surgery Is There a Benefit?
Abstract & Commentary
By Jonathan Abrams, MD, Professor of Medicine, Division of Cardiology, University of New Mexico, Albuquerque. Dr. Abrams serves on the speaker's bureau for Merck, Pfizer, and Parke-Davis.
Source: M. A. Koening, MD et al. Statin use and neurologic morbidity after coronary artery bypass grafting. Neurology. 2009;73:1.
Statins have been used in an increasing number and variety of conditions. This large, 10-year cohort study from John Hopkins Neurology Department and Cardiac Surgery Group uses a post-hoc analysis to examine the issue of whether statin use prior to Coronary Bypass Graft Surgery (CABG) would decrease post-op morbidity, specifically stroke and encephalopathy, as well as cognitive decline. Encephalopathy included delirium, mental status changes, and poor arousal occurring for more than 24 hours after CABG surgery. The basis of this study is the known statin modulated decrease in adverse outcomes in some studies after vascular procedures, such as carotid endarterectomy and arterial bypass. The post hoc analysis of consecutive patients undergoing CABG was undertaken in the decade 1997 to 2007. Patients were carefully followed for development of post-op neurologic deficits and CVA, including overt stroke. Careful post-op analyses were performed, usually by a neurologist. All new focal neurologic deficits were recorded; MRI and CT scans were often available (data not provided). Adverse outcomes were collated beginning 24 or more hours after surgery. Among a total of 5,121 CABG patients, 54% were taking pre-op statins. Use of statins prior to CABG rose from 35% in 1997, increasing to 60%-65% in 2007.
Results: Encephalopathy was noted in 8.6% of the cohort, and stroke was observed in 3.2%: overall, 11.8% or 604 patients met at least one primary endpoint. Statin users were also examined by propensity score, with no deviation from the main cohorts. Their adjusted propensity score was 0.958. MRI studies demonstrated multiple lesions in watershed territories; risk factors for watershed infarcts included intra-operative hypotension and arteriosclerosis, suggesting that strokes result from a combination of hypo-perfusion and emboli. There was no significant difference in CV mortality, MI, or length of stay between statin users and non-users. The authors conclude that preoperative statin use was not associated with a decreased incidence of stroke and encephalopathy post CABG.
This study is of clinical interest with the unexpected observation that pre-op statin use did not appear to be of benefit. Other reports are not consistent with this study, but none are as sophisticated, detailed, and well-designed as this trial. The patient base is quite large, with more than 5,000 subjects, half of whom were taking pre-operative statins. Given the still-increasing utilization of statins for a multitude of clinical conditions, it seems somewhat surprising that the results of statin usage are negative. It would seem that the endpoints of encephalopathy, overt stroke, and MI are clinically relevant and, somewhat surprisingly, statin use seemed ineffective in decreasing morbidity or mortality in post-CABG patients. The authors emphasize the role of watershed infarcts with multiple lesions in watershed territories. They suggest adverse outcomes occur due to a combination of hypo-perfusion and atheroemboli.
This is not a prospective, controlled trial. Prior use of statins is unknown, and the doses used prior to CABG were likely to have been inadequate in many patients. Also, statin potency has increased over the 10 years of this study. The authors do refer to a number of published reports with positive outcomes in other vascular beds, but they are much smaller and shorter studies, and not in CABG patients. However, a randomized, placebo-controlled trial would be unlikely to occur. Consequently, I recommend that patients who survive should be on a potent statin, especially in those with hypertension, diabetes, and all of the traditional risk factors. In most subjects, hopefully, high-dose statins will be used before a clinical event occurs. This report is somewhat unexpected, but it does not address the problem of relating the results to contemporary high-dose statin therapy and appropriate patient selection.