Epidemiological and case-control studies of heart failure estimate that systolic function is preserved in 40% to 50% of cases, which are thus presumed to be diastolic. However, the optimal treatment for diastolic heart failure has not yet been defined. Current American College of Cardiology/American Heart Association guidelines (Table I) emphasize the need to control the symptoms of diastolic heart failure by lowering left ventricular filling pressure without lowering cardiac output. This is important in that heart failure drugs have a narrow therapeutic window: an excessive reduction in preload can cause severe hypotension and low output.
Class I: diuretics and nitrates.
Both drug classes are INDICATED.
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They lower high left ventricular filling pressure by decreasing systemic and pulmonary venous return, thus alleviating symptoms. If right heart dilatation is present, they decrease ventricular interdependence and the restrictive effect of the pericardium. Careful dosage modulation is important, given the frequent dependence of these patients on preload reserve. ? Despite their clear symptomatic benefits, the effects of these drugs on prognosis are still unknown.
Class II: (3-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors.
Evidence for the efficacy of these POTENTIALLY USEFUL drugs remains inadequate. Though (3-blockade should lengthen ventricular relaxation a metabolically active process dependent on the efficacy of catecholamine-activated calcium reuptake by sarcoplasmic reticulum (3-blockers may also lower oxygen consumption (by slowing the heart rate), control hypertension, and inhibit ventricular hypertrophy and perhaps also fibrosis (two important determinants of diastolic dysfunction in coronary artery disease and hypertension). Moreover, like calcium channel blockers, (3-blockers control heart rate in atrial fibrillation, thus improving ventricular filling, which is notoriously hindered by the loss of atrial systole. Ongoing trials are investigating the efficacy of (3-blockade in heart failure with preserved systolic ventricular function. Calcium channel blockers act on diastolic dysfunction by controlling hypertension, lowering myocardial oxygen consumption, dilating the coronary microcirculation, and reversing hypertrophy. However, as with 13-blockers, their effects on survival and disease progression have yet to be determined.
Angiotensin-converting enzyme (ACE) inhibitors represent a major treatment strategy in systolic heart failure,
Class I Diuretics, nitrates, medications to control heart rate on atrial fibrillation, anticoagulants (if atrial fibrillation or past embolizations)
Class II Calcium channel blockers, (3-blockers, ACE inhibitors, anticoagulants for intracardiac thrombi.
Class III Positive inotropes if no diastolic dysfunction, treatment of asymptomatic arrhythmias.
Table I. Guidelines for the treatment of diastolic heart failure: American College of Cardiology/American Heart Association Task Force on Heart Failure.
After: Commitee on Evaluation and Management of Heart Failure. Guidelines for the evaluation and management of heart failure. Report of the Task force on Practice Guidelines. J Am Cell Cardiol. 1995;1376-1398. Copyright © 1995, Elsevier Science Ltd but are less frequently used in diastolic heart failure. Nevertheless, there is recent evidence of potential benefit. In the Vasodilator in Heart Failure Trials (V-HeFT), mortality in a small subgroup with heart failure and mild systolic dysfunction (ejection fraction [EF] >35%) treated with enalapril was lower not only than in patients with major systolic dysfunction, but also than in patients receiving hydralazine and isosorbide dinitrate. The lower mortality was due to a decrease in sudden deaths. The proposed mechanisms of these effects include the control of hypertension and reduction of ventricular mass in hypertensive patients, each of these factors being an important determinant of diastolic dysfunction. Ventricular hypertrophy secondary to pressure overload may also correlate with an increase in angiotensin II produced by the tissue ACE system, with secondary alteration of relaxation and increase of left ventricular filling pressure. Randomized multicenter studies of ACE inhibitors and angiotensin II receptor blockers, alone or in combination, are ongoing in populations with heart failure and preserved systolic function.
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Current European Society of Cardiology guidelines for treating diastolic heart failure do not greatly differ from those itemized above: they are based on (5-blockers, diuretics, and ACE inhibitors. The best treatment is to act on the possible causes (eg, constrictive pericarditis) and potential aggravating factors (eg, coronary artery disease, tachycardia, supraventricular arrhythmias, hypertension, left ventricular hypertrophy). New drug therapy data will be available in a few years.
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Drug; preserved systolic function; diuretic; nitrate; fi-blocker; calcium channel blocker; ACEI; vasodilator; positive inotrope.