Identify patients with significant LV systolic dysfunction who could benefit from specific pharmacologic therapies.

Left ventricular ejection fraction (LVEF) less than 0.40 is one of the strongest predictors of not only increased mortality, but also morbidity, including CHF and malignant arrhythmias. Pharmacologic therapy and/or revascularization can favorably affect this clinical course.

Accepted criteria for at least one assessment of LVF in patients with known CAD, include the following:

• Symptoms of CHF (e.g., orthopnea or paroxysmal nocturnal dyspnea)
• Significant impairments or decrement in exercise tolerance, due to dyspnea or fatigue
• Physical signs of CHF (e.g., elevated jugular venous pressure, unexplained pulmonary rales, laterally displaced point of maximal impulse, and S3 gallop)
• Cardiomegaly on chest x-ray
• Prior MI

Repeat assessment is indicated if there has been an unexplained worsening of CHF symptoms or signs or a significant decrement in exercise tolerance, due to fatigue or dyspnea. Routine reassessment of LVF in stable patients is not indicated.

It is also important to recognize that patients with normal or near-normal LVF (EF >0.40) may experience symptoms of heart failure due to diastolic LV dysfunction. Such patients may also experience symptomatic benefit from diuretics, beta-blockers or nitrates. For specific recommendations for the treatment of diastolic heart failure, the provider is referred to the ACC/AHA Task Force on Practice Guidelines, Guidelines for the evaluation and management of heart failure (2001).

DISCUSSION

Multiple studies have identified depressed LV systolic function as an independent risk factor for mortality (see The Multicenter Post Infarction Research Group report, 1983 and Bigger et al., 1984, specifically with respect to post infarct patients). ACE inhibitors, beta-blockers, and spironolactone have all been shown to improve survival in patients with LV systolic dysfunction. Also, these patients frequently have multi-vessel CAD and have the most to gain from revascularization procedures.

An echocardiogram can not only assess LV systolic function, but also identify wall motion abnormalities, valvular disease, and LV thrombus, all of which can significantly affect patient management. Accordingly, echocardiography is preferred to radionuclide ventriculography for this purpose for most patients (see Annotation E, Relative Advantages and Disadvantages of Echocardiography and Radionuclide Ventriculography for Assessing LVEF). LVEF is best performed at least 72 hours after any infarction, to allow for some recovery of "stunned" myocardium.