Defining diastolic dysfunction.

The human intellect has an almost irresistible urge to categorize and simplify. Thus, over the years, heart failure has been classified as forward or backward, right or left, compensated or decompensated. These distinctions, which were made primarily on the basis of data obtained from the history and physical examination, provided a conceptual framework for thinking about heart failure and for rationalizing therapeutic decisions (eg, digitalis to increase cardiac output in “forward” failure). As information routinely available to the clinician has been extended from the history and physical examination to now include precise, noninvasive characterization of ventricular volumes and aortic flow, it has been increasingly recognized that the pathophysiology of heart failure cannot be assessed adequately by the older classifications. For example, it is now appreciated that “backward” heart failure with elevated ventricular filling pressures and consequent pulmonary or peripheral edema can result from either systolic or diastolic ventricular dysfunction. In fact, epidemiological and casecontrol studies of individuals presenting with clinical heart failure have estimated that 40% to 50% of such patients have normal systolic function and presumed diastolic heart failure.1–4 For example, Senni et al,1 from the Mayo Clinic, reported that 43% of patients with clinical congestive heart failure and adequate echocardiographic assessment of ejection fraction show normal/preserved left ventricular function. Although the prognosis of patients with heart failure and preserved systolic function has generally been regarded as intermediate between normal subjects and patients whose heart failure is associated with depressed systolic function, the recent Mayo study1 calls this into question, showing both systolic and diastolic heart failure to have a similar prognosis, at least over the first 3 to 4 years of follow-up.