Stroke is a potentially devastating complication following cardiothoracic surgery with a reported incidence of between 2 and 10%. While numerous risk factors have been described for stroke, little data are available regarding its temporal relationship to the surgical procedure and whether this predicts long term outcomes.
In this study the authors retrospectively analysed data from 7839 isolated coronary artery bypass grafting (CABG) operations – 297 off-pump CABG, and 986 combined CABG and valve procedures – performed at a single centre between 1994 and 2004. The records of patients with signs of neurological complications were reviewed to identify 149 subjects with stroke at extubation (deemed to have ‘early stroke’, 1.6%) versus 99 patients having a symptom free interval (deemed to have ‘delayed stroke’, 1.1%). Survival data were then assessed, with a median follow-up time of 9.3 years (max 16.3 years).
Of note, ‘early’ and ‘delayed’ stroke had different risk factors with patients being at high risk for early stroke if they were of advanced age, had a high preoperative creatinine level, significant aortic atherosclerosis, or long cardiopulmonary bypass time (P<0.001 for all). Conversely, factors associated with delayed stroke were female gender (P<0.001), unstable angina (P=0.003), previous cerebrovascular disease (P=0.009), inotropic requirements (P<0.001), and postoperative atrial fibrillation (P<0.001). Stroke explained mortality not only in the early postoperative period (P<0.001), but also at long-term follow-up (P<0.001). Early and delayed stroke were associated with mortality hazard ratios (HRs) of 1.44 and 1.85 (P=0.008 and P<0.001), respectively. However, for patients surviving their first postoperative year, early stroke did not influence long-term mortality (HR 1.07, P=0.695). This was in contrast to delayed stroke (HR 1.71, P=0.001) suggesting the different risk factors associated with delayed stroke had implications for long term survival.
Early and delayed stroke post-CABG differ in their related risk factors, and in their impact on long-term prognosis. Further work may help to characterise patients at high risk for early and delayed stroke and lead to improved strategies to mitigate harm.
- Hedberg M, Boivie P, Engström KG. Early and delayed stroke after coronary surgery – an analysis of risk factors and the impact on short- and long-term survival. Eur J Cardiothorac Surg. 2011 Aug;40(2):379-87.