Diastolic heart failure is impairment in the filling of the left ventricle. Which of the following is LEAST likely to occur?

Diastolic dysfunction is an impairment in the filling of the left ventricle ("stiff ventricle") caused by decreased compliance at a normal left atrial pressure. Systolic heart failure, which is an impairment in contractility, has a better response to positive inotropic agents. Most patients have a combination of both systolic and dia­stolic dysfunction. In diastolic heart failure, filling of the left ventricle is slow or incomplete (i.e., decreased compliance) un­less left atrial pressures increase to maintain the ejec­tion fraction at the expense of increasing pulmonary and systemic venous congestion. Clinical findings in­clude dyspnea, which is the most common symptom, resulting from interstitial and pulmonary edema. Pathophysiologically, there is left atrial hypertension and pulmonary venous hypertension, leading to pul­monary congestion. Therapy is aimed at slowing the heart rate, which promotes filling of the left ventricle at low pressures. -Adrenergic blockers and calcium channel blockers are effective. Patients with diastolic dysfunction have a better survival rate than those with systolic dysfunction, because the ejection fraction is normal to slightly decreased, albeit at the expense of increased left atrial pressures. Systolic dysfunction is an impairment in contractil­ity of the left ventricle, or a defect in the ability of myofibrils to shorten against a load. The left ventricle loses its ability to eject blood into the aorta, so the ejection fraction (i.e., stroke volume/left ventricular end-diastolic volume) is decreased (usually < 40%); the normal ejection fraction is 80/120, or 66%, with a range of 55% to 75%. The ejection fraction is mea­sured by echo cardiography or radionuclide ventricu­lography. Signs of isolated systolic dysfunction include fatigue, prerenal azotemia, cool skin, and mental obtundation. The left ventricular chamber eventually dilates and patients develop fatigue, dyspnea, and pe­ripheral edema, which are signs of right-sided heart failure. Examples of systolic dysfunction include post­ myocardial infarction, ischemic injury (e.g., acute myocardial infarction), and congestive cardiomyopa­thy. Therapy is aimed at improving the performance of the left ventricle with administration of positive inotropic agents and peripheral vasodilators to de­crease peripheral resistance.