Complication rates after left- versus right-sided carotid endarterectomy.

BACKGROUND: Studies suggest that the side of carotid endarterectomy (CE) may influence the rate of postoperative complications. We sought to clarify this by (1) analysis of individual-level data from 3 large studies and (2) systematic review and meta-analysis of additional published descriptions of outcomes by side. METHODS AND RESULTS: The Western Canada Carotid Endarterectomy (WCCE) study (n=3164) was analyzed for outcomes by side along with data from the North American Symptomatic Carotid Endarterectomy Trial (NASCET; n=1415), and the ASA [Acetylsalicylic Acid] in Carotid Endarterectomy Trial (ACE; n=2469). Pooled analysis of individual-level data from these three studies allowed calculation of rate ratios for stroke or death by side. Medline and EMBASE were searched to identify additional studies reporting CE outcomes by side, and an overall risk ratio for outcomes by side was determined with fixed-effects meta-analysis. The WCCE in-hospital stroke or death rates for left and right-sided CE were 3.72% and 3.07%, respectively (P=0.27). A pooled analysis of the NASCET and ACE trials also revealed higher stroke or death rates for left-sided CE (5.39% versus 2.96%; P<0.001). The corresponding risk-adjusted rate ratios for stroke or death for left- versus right-sided surgery were 1.22 (95% CI, 0.83 to 1.77) for WCCE and 1.82 (1.32 to 2.50) for the pooled NASCET and ACE trials. Systematic review of the literature identified 2 additional studies. Meta-analysis of all 5 available studies yielded a corresponding pooled rate ratio for stroke or death of 1.36 (1.18 to 1.56). CONCLUSIONS: Left-sided CE is consistently associated with higher postoperative adverse event rates. Research into potential mechanisms is required to explain and address this finding.