Preserved versus reduced left ventricular systolic function: Which is more serious?

In the past 20 years, the syndrome of heart failure associated with normal or near-normal left ventricular ejection fraction has been increasingly recognized. Several studies have reported that, among elderly heart failure patients, approximately 50% have preserved left ventricular systolic function. This syndrome, often referred to as diastolic heart failure, is more common in women and in persons with antecedent hypertension.1,2

Because patients with diastolic heart failure differ in many respects from those with systolic heart failure, the clinical course and prognosis of patients with diastolic heart failure has been the subject of some debate. The severity of left ventricular systolic dysfunction, as assessed by the ejection fraction, is widely recognized as an important independent predictor of mortality. As a result, diastolic heart failure is often perceived as milder or less serious. But is this true?

In the report by Gustafsson and colleagues (page 22), there was a direct relationship between wall-motion index, which is a measure of left ventricular systolic function that correlates with ejection fraction, and long-term survival among a representative sample of more than 5,000 patients hospitalized with heart failure. Thus, patients with a normal or near-normal wall-motion index had significantly better survival at 5 to 8 years of follow-up than patients with a markedly reduced wall-motion index. These findings are consistent with most, but not all, previous studies.1,3,4 As the authors are quick to point out, patients with heart failure and a normal wall-motion index still had a dismal

prognosis, with 19% dying within

1 year of diagnosis, and 50% being dead within 5 years, a survival rate that is worse than for most forms of cancer.5

Mortality, however, is not the only relevant outcome in patients with heart failure. Heart failure is a chronic condition associated with substantial morbidity, including impaired exercise tolerance, diminished quality of life, and frequent hospitalizations. For many older patients, the impact of heart failure on quality of life is of greater importance than its effect on survival. It

is therefore of considerable clinical

relevance that the effects of diastol-

ic heart failure on each of these outcomes are virtually identical to

those of systolic heart failure. In a recent prospective study, for example, symptom severity, exercise tolerance, and quality of life were similar in heart failure patients with normal left ventricular systolic function compared with those with reduced left ventricular systolic function.6 Similarly, numerous studies have shown that hospitalization rates are similar in heart failure patients with impaired or preserved left ventricular systolic function.7,8

Conclusion

So is diastolic heart failure milder or less serious than systolic heart failure? The answer is, emphatically, no! Indeed, from the public health perspective, it can be said that dia-stolic heart failure is more serious than systolic heart failure in the elderly, because the overall toll of diastolic heart failure, in terms of attributable morbidity and mortality, is greater than that for systol-

ic heart failure.9 The findings of Gustafsson and colleagues are in accordance with this viewpoint and clearly support the need for intensive research to develop more ef-

fective strategies for the treatment and prevention of diastolic heart failure in our progressively aging population.