A team of researchers from the University of California, Los Angeles analyzed data from a heart failure patient registry and concluded that pneumonia, irregular heartbeat and obstructed blood flow to the heart are the most common reasons for hospitalization for heart failure in the U.S.

The study, known as Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients with Heart Failure (OPTIMIZE-HF), analyzed the factors that most often led to hospital admissions for heart failure patients between March 2003 and December 2004. During this period, almost 49,000 patients were hospitalized in 259 medical institutions across the U.S.

According to the findings, the factors responsible for hospitalizations in heart failure patients include: pneumonia or respiratory ailments (15.3 percent); obstructed blood flow to the heart (14.7 percent); irregular heart beat or arrhythmia (13.5 percent); uncontrolled hypertension (10.7 percent); not taking medications (8.9 percent); worsening kidney function (6.8 percent); and not adhering to a special diet (5.2 percent).

“Over 60 percent of hospitalized heart failure patients had at least one of these precipitating factors at hospital admission,” study first author Dr. Gregg C. Fonarow, UCLA's Eliot Corday Chair in Cardiovascular Medicine and Science and director of the Ahmanson-UCLA Cardiomyopathy Center, said in a prepared statement, according to the Washington Post. “Understanding the factors that can exacerbate heart failure and lead to hospitalizations -- especially the ones that are avoidable -- are invaluable to help us improve management of heart failure.”

Authors determined that in-hospital mortality rates were lower in patients with none of these factors compared to those with one or more of them. The study found that pneumonia, ischemia and worsening renal function were independently associated with higher in-hospital mortality, and ischemia and worsening renal function were associated with a higher risk of follow-up mortality.

On the other hand, uncontrolled hypertension was associated with lower in-hospital mortality and lower post discharge death/re-hospitalization.

“Learning how these factors influence length of hospital stay, mortality and re-hospitalization are key to helping us better manage patients and preventing future hospitalizations,” Dr. Fonarow said.

Five million Americans suffer from heart failure and nearly 3.6 million hospitalizations each year are attributed to the condition, which occurs when the heart is not able to pump enough blood to the body’s other organs.

The study, sponsored by GlaxoSmithKline, appeared in the April 28 edition of the Archives of Internal Medicine.