The Risk of Adverse Cardiac Events after Pneumonia in Patients with Coronary Artery Disease

Rationale: Pneumonia triggers an inflammatory response that can persist even after the infection is resolved. This may further increase the risk of major adverse cardiac events (MACE) in individuals with known coronary artery disease (CAD), though this remains unclear. Objectives: We aimed to assess the impact of pneumonia on MACE in individuals with existing CAD. Methods: We identified patients who had coronary artery revascularization procedures in seven major hospitals in Western Australia between 2000 and 2005. Multivariable Cox regression models assessed the association between time-dependent pneumonia and MACE (composite of all-cause death + myocardial infarction + unstable angina + ischemic stroke + heart failure) and component outcomes separately, over 30 days, 1 year, and full follow-up. Results: There were 14,425 patients in the study cohort (mean age, 64.4 yr; 23.6% female). Over a maximum of 13 years of follow-up, 988 patients experienced one or more pneumonia hospitalization. The risk of MACE increased over time, with adjusted hazard ratios (aHRs) of 4.91 (95% confidence interval [CI], 1.21-20.00) and 4.91 (95% CI, 2.62-9.19) over 30-day and 1-year intervals, respectively, and an aHR of 11.41 (95% CI, 9.22-14.11) over the entire follow-up. Myocardial infarction risk was highest during the first 30 days (aHR, 11.34) and reduced over the 1-year interval and the remainder of follow-up (aHR, 2.27 and 2.63, respectively). Risk of heart failure and cardiovascular death were also high over the entire follow-up period (aHR, 10.39 and 12.25, respectively). Conclusions: Pneumonia hospitalization is associated with a significantly increased risk of MACE in patients with CAD. Underlying mechanisms should be better understood to develop targeted interventions to reduce MACE in this already high-risk population.