Immunization and the ACS Patient: A Crucial, Yet Sometimes Confusing Connection
For patients with cardiovascular disease—including those who have experienced Acute Coronary Syndromes (ACS)—immunization is a critical part of secondary prevention and long-term health maintenance. Yet, paradoxically, some vaccine-related reactions can temporarily mimic the symptoms of cardiac events, raising diagnostic challenges for both patients and providers.
The Case for Immunization in ACS Patients
Patients with coronary artery disease are particularly vulnerable to complications from infections such as influenza, pneumococcus, and COVID-19. These pathogens can provoke systemic inflammation, endothelial dysfunction, and prothrombotic states—leading to plaque destabilization and acute ischemic events. Vaccination, by reducing the incidence and severity of these infections, offers significant cardiovascular protection.
Evidence continues to mount. A 2023 review in the European Heart Journal Supplements reinforced that seasonal influenza epidemics are linked with spikes in myocardial infarctions and cardiovascular deaths. Influenza vaccination has been associated with a ~30–45% reduction in major adverse cardiovascular events (MACE), particularly among patients with recent ACS (within 12 months). These benefits appear comparable to other established secondary prevention strategies such as statins and beta-blockers.
The Canadian Cardiovascular Society (CCS) and the Public Health Agency of Canada (PHAC) both recommend annual influenza vaccination for patients with atherosclerotic cardiovascular disease, as well as COVID-19 boosters and pneumococcal vaccination in accordance with age and comorbidity guidelines. Yet uptake remains suboptimal—creating an opportunity for clinicians to actively close this evidence-to-practice gap.
The Other Side of the Coin: Vaccine Reactions and Cardiac Mimics
While vaccines are overwhelmingly safe, side effects occasionally mimic cardiac symptoms. These include:
Musculoskeletal or pleuritic chest pain, often localized to the injection side
Fatigue, myalgias, and low-grade fever
Palpitations or tachycardia, typically self-limited
Rarely, myocarditis or pericarditis has been reported, especially in males under 30 after mRNA COVID-19 vaccination. According to CDC data, the rate in this group is approximately 12–39 cases per million doses—much lower in older adults. Importantly, post-vaccine myocarditis is usually mild and self-limited.
Clinical Implications: A Balanced Approach
Clinicians caring for ACS patients should:
Incorporate vaccine discussions into discharge planning and follow-up visits
Prepare patients for expected mild side effects, reassuring them that these are not signs of relapse
Maintain vigilance for true ischemia, particularly when symptoms are atypical or persistent
Avoid dismissing chest symptoms as benign without clinical assessment, especially in high-risk individuals
A Shared Goal
By reducing preventable infections, immunization supports long-term cardiovascular health and reduces readmissions. Encouraging vaccinations while acknowledging their occasional side effects helps patients make informed choices and supports appropriate care decisions.
In our ACS population, the benefits of immunization far outweigh the risks. Let’s ensure this preventive tool remains a standard part of cardiovascular care.
References
Udell JA, Zawi R, Bhatt DL, et al. Association between influenza vaccination and cardiovascular outcomes in high-risk patients: a meta-analysis. JAMA. 2013;310(16):1711–1720. doi:10.1001/jama.2013.279206
de Andrade D, Díaz J, Panhuyzen-Goedkoop N, et al. Vaccines and cardiovascular outcomes: lessons learned from influenza epidemics. Eur Heart J Suppl. 2023;25(Suppl A):A17–A24. doi:10.1093/eurheartjsupp/suac110
Centers for Disease Control and Prevention. Clinical Considerations: Myocarditis after COVID-19 Vaccines. https://www.cdc.gov/vaccines/covid-19/clinical-considerations/myocarditis.html
Canadian Immunization Guide: Influenza Vaccine. Public Health Agency of Canada. https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-10-influenza-vaccine.html
