Bacterial Pneumonia Linked With Increased Risk for Cardiac Events

Patients hospitalized with acute pneumonia are at increased short-term risk of major adverse cardiovascular events (MACE), but it has been widely unknown which type of pneumonia is associated with a greater risk.

In a new study conducted by investigators from the Intermountain Heart Institute at Intermountain Medical Center in Salt Lake City, it was discovered that patients diagnosed with bacterial pneumonia had a 60% greater risk of a MACE such as heart attack (MI), stroke, or death than patients who had been diagnosed with viral pneumonia.

"We've always known pneumonia was a risk factor for a major adverse cardiac event, like a heart attack, within the first 90 days of being diagnosed," J. Brent Muhlestein, MD, a cardiovascular researcher with the Intermountain Heart Institute at Intermountain Medical Center said in a recent statement. "What we didn't know was which type of pneumonia was more dangerous. The results of this study provided a clear answer, which will allow physicians to better monitor patients and focus on reducing their risk of a major adverse cardiac event."

Study investigators evaluated 4792 patients diagnosed with pneumonia who were hospitalized across 23 hospitals between January 2007 and May 2014. Following diagnosis, the patients were followed for 90 days and any MACE events were noted.

Of the 4792 total patients, 3736 (78%) were diagnosed with bacterial pneumonia and 993 (21%) were diagnosed with viral pneumonia. A total of 61 (1%) patients tested positive for both bacterial and viral pneumonia.

A total of 1531 (32%) patients had a MACE within 90 days, including all-cause mortality (n = 547, 11%), MI (n = 18, <1%), stroke (n = 37, 1%), or heart failure (n = 1192, 25%).

The incidence of 90-day MACE was 1270 (34%) after bacterial pneumonia and 258 (26%) after viral pneumonia (adjusted odds ratio = 1.6 [95% CI: 1.27, 2.02, P = .002]).

The investigators hypothesize that the reason for increased MACE events is related to bacterial pneumonia, causing greater inflammation of the arteries in comparison to viral pneumonia. When the arteries are inflamed, it causes destabilization of the layers of plaque that have built up which can then break loose from the artery wall, cause a blockage, which can then lead to a heart attack, stroke, or death.

"The practical result of our study is that caregivers should be aware of the greater cardiovascular risks associated with respiratory infections like pneumonia, and especially bacterial pneumonia," Dr. Muhlestein said. "If a patient has been diagnosed with bacterial pneumonia, treat it aggressively and watch them closely for any signs of a heart attack or stroke. If the patient is taking medications specific to a heart condition, like high blood pressure or cholesterol, they should continue taking those prescribed medications."

The investigators recommend that individuals with known plaque build-up should take extra precautions to prevent respiratory infections, including getting a flu shot and a pneumovax, and practicing proper hand hygiene.

Results of the study “Bacterial Pneumonia Compared to Viral Pneumonia is Associated With a Higher Risk of Future Major Adverse Cardiovascular Events,” were presented during the American Heart Association Scientific Sessions in Chicago, Illinois, on Sunday, November 11, 2018.