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Some factors related to heart function and linked with heart failure more common than believed

November 08, 2006

Several factors related to heart function and that play a role in heart failure are more prevalent than previously thought, according to a study in the November 8 issue of JAMA.

Heart failure (HF) is a highly prevalent illness with various causes, which may be associated with reduced or preserved ejection fraction (EF; the fraction [volume] of blood pumped out of the ventricle of the heart with each heart beat). Reduced EF is less than 50 percent; preserved EF, 50 percent or greater. There is disagreement on the prevalence, characteristics and outcomes of heart failure and preserved EF, and the prevalence of diastolic dysfunction (or diastolic heart failure; when the heart contracts normally but the ventricles do not relax properly and less blood enters the heart during normal filling).

Francesca Bursi, M.D., M.Sc., formerly of Mayo Clinic and Foundation, Rochester, Minn., and colleagues examined the prevalence of preserved and reduced EF and that of diastolic dysfunction among all residents treated for heart failure in Olmsted County, Minn. The study, conducted from September 2003 to October 2005, included 556 participants who underwent assessment of EF and diastolic function by echocardiography and measurement of brain natriuretic peptide (BNP; a substance secreted from the heart in response to changes that occur when heart failure develops or worsens). Blood levels of BNP increase when heart failure worsens and decrease when the heart failure condition is stable.

The researchers found that of the 556 patients with heart failure, 55 percent had preserved EF. Compared with their counterparts with reduced EF, patients with preserved EF were older, more likely to be women and less likely to be smokers or have a history of heart attack. Diastolic dysfunction was present in 80 percent of patients, combined systolic and diastolic dysfunction was present in 37 percent, and isolated diastolic dysfunction was present in 44 percent.

Patients with reduced EF were more likely to have moderate or severe diastolic dysfunction than their counterparts with preserved EF. Both low EF and diastolic dysfunction were independently related to higher levels of BNP. At 6 months, the number of deaths was 16 percent for both preserved and reduced EF (compared with an expected rate of death of 4 percent and 3 percent, respectively).

"The prevalence of moderate and severe diastolic dysfunction among patients with HF and preserved EF was strikingly higher than that observed in elderly patients with cardiovascular disease but without HF in the same community, supporting the hypothesis that diastolic dysfunction is present in a large segment of patients presenting with HF and preserved EF. Similarly, the high prevalence of moderate and severe diastolic dysfunction in patients with HF and reduced EF supports the importance of diastolic dysfunction in both forms of HF. The importance of characterizing the pathophysiology of HF with preserved EF is underscored by the high mortality rate of these patients, which is comparable to that of patients with reduced EF," the authors conclude.

JAMA and Archives Journals