We read with interest the report by Cangemi et al “Relation of cardiac complications in the early phase of community-acquired pneumonia (CAP) to long-term mortality and cardiovascular events” published in the August 5th issue of the American Journal of Cardiology . The investigators show that 18% of patients with CAP study develop intrahospital cardiac complications, defined as myocardial infarction (MI) and atrial fibrillation. Furthermore, the investigators prospectively show that these cardiac complications in the early phase of CAP are associated with adverse long-term cardiovascular prognosis (with the end point being cardiovascular death, nonfatal MI, and stroke). We commend the investigators on their work. We would also like to ask for some clarifications because we think that the subject of cardiac complications during CAP hospitalization merits more clinical and scientific attention.

The investigators have previously demonstrated a high MI rate (especially of silent MI) in patients with CAP during the first days of hospitalization. This MI rate of 11% was higher than in previous reports, which is probably explained by the use of high-sensitivity troponin (instead of creatine kinase, a less sensitive biomarker of myocardial injury) and by the levels of high-sensitivity troponin that were measured not only at hospital baseline but also every 12 hours during hospital admission. Furthermore, the investigators suggested that high platelet activation may be the mechanistic explanation for this increased MI risk in CAP, which is consistent with the essential role of platelets in MI.

Nonetheless, all the studies about cardiac complications during CAP hospitalizations have clearly shown a much higher risk of heart failure compared with MI. A meta-analysis of 25 studies found increased cumulative rates of heart failure (14%), arrhythmias (5%), and MI (5%). Those data were confirmed by the analysis of a prospective multicenter cohort of 2,344 unselected patients with CAP ; in this cohort, the 30-day incidence of heart failure, arrhythmia, and MI was 21%, 10%, and 3%, respectively, with this risk peaking in the first 2 days of hospitalization.

Given that heart failure is a much more frequent complication during CAP hospitalization than MI, we would like to ask the investigators what was the incidence of heart failure in their study. Additionally, we would like to know whether heart failure in the early phase of CAP is also associated with adverse long-term cardiac prognosis (as they have demonstrated to be the case with MI during the early phase of CAP). Being a prospective study, SIXTUS (thromboSIs-related eXTra-pulmonary oUtcomeS in pneumonia) study is ideal to solve that question without bias. The answer to both questions may indicate that outcomes of patients with CAP can be improved by prevention of associated cardiac complications, which is obviously a call to arms for improving the prognosis of patients with CAP by means of enhancing cardiac care.