Clinical Review

The Burden of Cardiac Complications in Patients with Community-Acquired Pneumonia


 

References

Two methods used to prevent cardiac complications in general have been administration of aspirin and statins. The anticlotting properties of aspirin help to maintain blood flow in arteries narrowed by atherosclerosis. A meta-analysis of 10 randomized controlled trials found a statistically significant association between aspirin and a benefit on nonfatal myocardial infarctions/coronary events [35]. The associations were found with doses of 100 mg or less daily, and benefits were seen within 1 to 5 years. Statins have also been found to reduce all-cause mortality, cardiac-related mortality, and myocardial infarction [36]. A statin may stabilize coronary artery plaques that otherwise may rupture and cause myocardial ischemia or an infarct. But statins have also been found to be associated with a decreased risk of CAP. A comprehensive systematic review and meta-analysis found a decreased risk of CAP (OR 0.84; 95% CI, 0.74– 0.95) and decreased short-term mortality in patients with CAP (OR 0.68; 95% CI, 0.56–0.78) as a result of statin therapy [37]. The studies included any of 8 available statins. A prospective observational study found that patients who had been on a statin prior to being admitted for CAP had lower mortality, a lower incidence of complicated pneumonia and a lower C-reactive protein [38]. The lower C-reactive protein identifies decreased inflammation, which translates into improved endothelial function, modulated antioxidant effects, and a reduction in pro-inflammatory cytokines, hence its association with less severe CAP. Further study may reveal that a certain patient population should receive a statin to prevent CAP and improve outcomes. Overall, data support taking aspirin to prevent cardiac events regardless of CAP; further investigation of the benefits of statins to prevent cardiac complications in CAP patients is needed.

Clinical Applications

There are several implications of knowing the relationship between cardiac complications and CAP. First, physicians can better inform their patients about risks once they have been diagnosed with pneumonia. Second, physicians may be more likely to recognize a complication early and provide appropriate intervention. Third, physicians can risk stratify patients using the prediction score for cardiac complications in CAP patients [28]. In 1931 Master et al found that some patients with CAP also had PR interval or T-wave changes present for about 3 days, so they recommended obtaining an ECG to determine when a patient might be able to be discharged or declared “cured” [39]. Now, we are similarly recommending obtaining an ECG in CAP patients, but upon admission, in order to identify those who may get ischemic changes, arrhythmias or QTc prolongations. Pro-brain natriuretic peptide and troponins may be obtained independently of ECG results, and a cardiac echocardiogram may be reserved for those with a high risk of complications [40]. Finally, we recommend screening all patients for need for influenza and pneumococcal vaccines and administering according to the Advisory Committee on Immunization Practices of the Centers for Disease and Prevention [33].

Research Implications

The fact that cardiac complications in CAP patients is a well-defined entity with a significant degree of morbidity and mortality should prompt attentiona and resources to be directed to this area. The prediction score created specifically for this subpopulation of patients [28] can improve research by allowing adequate risk stratification to efficiently design and execute studies. Studies may be designed with fewer patients required to be enrolled while maintaining statistical power by limiting subject inclusion criteria to certain risk classes. Specific areas of future investigation should include the mechanisms of pathophysiology, which are not completely understood, and other complications, such as pulmonary edema, infectious endocarditis and pericarditis. Finally, cost has not been studied in this area or the potential savings of recognizing and preventing cardiac complications.

Next Article: