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The presence of moderate or severe diastolic dysfunction in patients with preserved systolic function independently predicted mortality, a retrospective study determined.

After propensity matching to limit the confounding effects of factors such as hypertension, age, diabetes, and obesity, the hazard ratio for mortality with moderate diastolic dysfunction was 1.58 (95% CI 1.20 to 2.08, P<0.001), according to Wael A. Jaber, MD, and colleagues from the Cleveland Clinic.

In addition, the hazard ratio associated with severe diastolic dysfunction was 1.84 (95% CI 1.29 to 2.62, P<0.001), the researchers reported in the June 27 Archives of Internal Medicine.

However, mild diastolic dysfunction did not predict mortality (HR 1.11, 95% CI 0.85 to 1.47, P=0.45).

"Our study provides the physician with a prognostic context when [diastolic dysfunction] is reported," observed Jaber and colleagues.

Severe diastolic dysfunction is a recognized risk factor for mortality, but because many associated medical conditions also predict mortality, the question of whether the diastolic dysfunction is a true predictor has remained unanswered.

To address this, and to explore the effects of the severity of diastolic dysfunction, Jaber's group examined the clinical records and echocardiographic evaluations of 36,261 patients who had normal systolic function as shown by an ejection fraction of 55% or higher.

The patients' mean age was 58.3 years and 54.4% were women.

Reasons for patients being referred for echocardiography included evaluation of valvular and ventricular function, coronary artery disease, and arrhythmias.

Cardiovascular risk factors were common among the cohort, but conditions such as congestive heart failure and coronary artery disease were unusual.

A total of 65.2% of patients had diastolic dysfunction, with 60% being mild, 4.8% moderate, and 0.4% severe.

Echocardiographic findings in mild diastolic dysfunction include abnormalities in relaxation of the myocardium and normal left atrial pressure, while in moderate and severe dysfunction findings include increased left atrial pressure and impaired left ventricular relaxation.

Characteristics associated with diastolic dysfunction in this cohort included male sex, age older than 65, obesity, and the presence of cardiovascular risk factors or established heart disease (P<0.001 for all).

Diastolic dysfunction also was more likely in patients with other chronic conditions such as chronic renal failure.

Among the entire cohort, 5,789 patients died.

In an unadjusted analysis, 7% of patients with normal diastolic function died, as did 21% of the mild diastolic dysfunction group, 24% of the moderate group, and 39% of the severe group.

The researchers then performed propensity matching and included 1,249 patients in a further analysis. In this group there were 379 deaths.

Eight-year survival for those with normal diastolic function was 78%, compared with 72%, 68%, and 58% of the mild, moderate, and severe groups.

Further studies will be needed to examine mechanisms by which moderate and severe diastolic dysfunction influence mortality and to explore the potential for therapeutic intervention, the researchers noted.

They pointed out a number of limitations to their study, including its retrospective design and single-center population, and the use of ejection fraction to measure systolic function.

In addition, they included clinical data only from six months before to six months after the echocardiographic testing, and relied on ICD-9 codes for diagnoses.

In a commentary accompanying the study, Ileana L. Piña, MD, of Case Western Reserve University in Cleveland, observed that full understanding of diastolic dysfunction as a continuum is a puzzle gradually being pieced together.

The investigators in this study "provide an important piece of the puzzle (i.e., that diastolic dysfunction is common and that physicians need to be aware of the prognostic value of moderate and severe diastolic dysfunction)," she wrote.