A study in the 1980s that reported 3 of 38 CAP patients with CHF interrupted the paucity of data at the time that showed that having a cardiac complication during CAP was a known entity . By the end of the 20th century, Meier et al noted that among case patients who had an MI, an acute respiratory tract infection preceded the MI in 2.8% while in only 0.9% of control patients . They also noted that patients who had an acute respiratory tract infection were 2.7 times more likely to have an MI in the following 10 days than control patients.
Further study by Musher et al revealed that MI was associated with pneumococcal pneumonia in 12 (7%) of 170 veteran patients . An MI was defined on the basis of ECG abnormalities (Q waves or ST segment elevation or depression) with troponin I levels ≥ 0.5 ng/mL. They also evaluated arrhythmias and CHF. They included atrial fibrillation or flutter and ventricular tachycardia while excluding terminal arrhythmias. An arrhythmia was found in 8 (5%) patients. CHF was based on Framingham criteria ( Table 1 ) . New or worsening CHF was determined by comparing physical findings, laboratory values, chest radiograph, and echocardiogram reports in medical records. CHF was found in 13 (19%) patients. Ramirez et al found that MI was associated with CAP in 29 (5.8%) of 500 similar veteran patients .
Corrales-Medina et al reported cardiac complications in CAP patients in the Pneumonia Patient Outcomes Team cohort study . They defined MI as the presence of 2 of 3 criteria: ECG abnormalities, elevated cardiac enzymes, and chest pain. They found 43 (3.2%) of 1343 patients with an MI. Arrhythmias included atrial fibrillation or flutter, multifocal atrial tachycardia, supraventricular tachycardia, ventricular tachycardia (≥ 3 beat run) or ventricular fibrillation. With the more inclusive list, they found a greater proportion, 137 (10%) patients affected. They defined CHF with physical examination findings plus a radiographic abnormality, and found 279 (21%) patients affected. A meta-analysis of 17 studies had pooled incidences for an MI of 5.3%, an arrhythmia of 4.7% and CHF of 14.1% .
In summary, the most prominent cardiac complications in patients with CAP have been found to be CHF, MI, and arrhythmia.
Timing of Cardiac Complications in Relation to CAP
While a patient is still in the community, cardiac complications may occur with the onset of CAP, or afterwards. For these patients, the primary goal is to identify the complication and manage it as soon as the patient is admitted for CAP, rather than allowing the complications to worsen only to be recognized later. Cardiac complications are rare in outpatients overall. A study of 944 outpatients found heart failure in 1.4%, arrhythmias in 1.0% and MI in 0.1% .
For patients who are admitted with CAP but who do not have a cardiac complication, the goals are either to prevent any complication or to recognize and manage a complication early. This also applies to patients who have been discharged after an admission for CAP. Cardiac complications have been recorded shortly after (within 30 days), and late (up to 1 year) after discharge. A study of over 50,000 veterans who were admitted for CAP were followed for any cardiovascular complication in the next 90 days. Approximately 7500 veterans were found to have a cardiac complication, including (in order of highest to lowest frequency) CHF, arrhythmia, MI, stroke and angina . More than 75% of the complications were found on the day of hospitalization, but events were still measured at 30 days and 90 days.