Little is known about the association between chronic obstructive pulmonary disease (COPD) and cardiovascular disease (CVD) in people with established CVD. Knowing if COPD is associated with a higher risk of cardiovascular events would guide appropriate secondary prevention.

To examine the risk of COPD on major adverse cardiac events (MACEs, acute myocardial infarction, stroke and cardiovascular death) in a complete real-world population of a large province, with known CVD.

We conducted a retrospective population cohort study using health administration, medication, laboratory, electronic medical record and other data from Ontario, Canada. All people with a history of CVD with and without physician-diagnosed COPD as of 2008 were followed until 2016 and cardiac risk factors, sociodemographic factors, comorbidities and other factors were compared. Sequential cause-specific hazard models adjusting for these factors determined the risk of MACE in people with COPD.

Of 496 056 individuals with CVD in Ontario on 1 January 2008, 69 161 (13.9%) had COPD. MACE occurred more frequently among those with CVD (45.3 per 1000 person-years) and COPD compared with those with CVD alone (28.6 per 1000 person-years) (HR 1.24, 95% CI 1.21–1.26) after adjustment for cardiac risk factors, comorbidities, socioeconomic status and other factors. People with COPD were less likely to receive preventive CVD medications or see a cardiologist.

In a large, real-world population of people with established CVD, COPD was associated with a higher rate of cardiovascular events but a lower rate of preventive therapy. Strategies are needed to improve secondary CVD prevention in the COPD population.

Data are available upon reasonable request. The dataset from this study is held securely in coded form at ICES. While legal data sharing agreements between ICES and data providers (eg, healthcare organisations and government) prohibit ICES from making the dataset publicly available, access may be granted to those who meet prespecified criteria for confidential access, available at www.ices.on.ca/DAS (email: [email protected]). The full dataset creation plan and underlying analytic code are available from the authors upon request, understanding that the computer programs may rely upon coding templates or macros that are unique to ICES and are therefore either inaccessible or may require modification.