From the Division of Infectious Diseases, School of Medicine, University of Louisville, Louisville, KY.
- Objective: To summarize the published literature on cardiac complications in patients with community-acquired pneumonia (CAP) as well as provide a historical context for the topic; and to provide recommendations concerning preventing and anticipating cardiac complications in patients with CAP.
- Methods: Literature review.
- Results: CAP patients are at increased risk for arrhythmias (~5%), myocardial infarction (~5%), and congestive heart failure (~14%). Oxygenation, the level of heart conditioning, local (pulmonary) and systemic (cytokines) inflammation, and medication all contribute to the pathophysiology of cardiac complications in CAP patients. A high Pneumonia Severity Index (PSI) can be used to screen for risk of cardiac complications in CAP patients; however, a new but less studied clinical rule developed to risk stratify patient hospitalized for CAP was shown to outperform the PSI. A troponin test and ECG should be obtained in all patients admitted for CAP while a cardiac echocardiogram may be reserved for higher-risk patients.
- Conclusions: Cardiac complications, including arrhythmias, myocardial infarctions, and congestive heart failure, are a significant burden among patients hospitalized for CAP. Influenza and pneumococcal vaccination should be emphasized among appropriate patients. Preliminary data suggest that those with CAP may be helped if they are already on aspirin or a statin. Early recognition of cardiac complications and treatment may improve clinical outcomes for patients with CAP.
Community-acquired pneumonia (CAP) is a common condition in the United States and a leading cause of morbidity and mortality [1,2], with medical costs exceeding $10 billion in 2011 . The mortality rate is much higher for those aged 65 years and older . Men have a higher death rate than women (18.6 vs. 13.9 per 100,000 population), and death rate varies based on ethnicity, with mortality rates for American Indian/Alaska natives at 19.2, blacks at 17.1, whites at 15.9, Asian/Pacific Islanders at 15.0, and Hispanics at 13.1 (all rates per 100,000) . CAP causes considerable worldwide mortality, with differences in mortality varying according to world region .
Cardiovascular complications and death from other comorbidities cause a substantial proportion of CAP-associated mortality. In Mortensen et al’s study, among patients with CAP who died, at least one third had a cardiac complication, and 13% had a cardiac-related cause of death . One study showed that hospitalized patients with CAP complicated by heart disease were 30% more likely to die than patients hospitalized with CAP alone . In this article, we discuss the burden of cardiac complications in adults with CAP, including underlying pathophysiological processes and strategies to prevent their occurence.
Pathophysiological Processes of Heart Disease Caused by CAP
The pathophysiology of cardiac complications as a result of CAP is made up of several hypotheses, including (1) declining oxygen provision by the lungs in the face of increasing demand by the heart, (2) a lack of reserve for stress because of cardiac comorbidities and (3) localized (pulmonary) inflammation leading to systemic (including cardiac) complications by the release of cytokines or other chemicals. Any of these may result in cardiac complications occurring before, during, or after a patient has been hospitalized for CAP. Antimicrobial treatment, specifically azithromycin, has also been implicated in myocardial adverse effects. Although azithromycin is most noted for causing QT prolongation, it was associated with myocardial infarction (MI) in a study of 73,690 patients with pneumonia . A higher proportion of those who received azithromycin had an MI compared to those who did not (5.1% vs 4.4%; OR 1.17; 95% CI, 1.08–1.25), but there was no statistical difference in cardiac arrhythmias, and the 90-day mortality was actually better in the azithromycin group (17.4% vs 22.3%; odds ratio [OR], 0.73; 95% CI, 0.70–0.76).