Commentary

It is important to identify patients with symptoms of congestive heart failure who have LVSD because their survival can be lengthened and symptoms alleviated by the medical armamentarium. It is equally important to rule out the diagnosis of LVSD to avoid treatment with medications that are potentially harmful in other conditions (eg, digoxin in the case of diastolic dysfunction or β-adrenergic blocking agents for pulmonary disease).

2 possible approaches exist for identifying symptomatic patients with LVSD: echocardiography in all presenting patients and echocardiography in a high risk subset of patients. The former is common practice because of the implications of missing the diagnosis. Nielsen et al studied 3 indices that might identify the subset of patients who have signs or symptoms of heart disease and who are most likely to have LVSD: electrocardiography, which is sensitive but not specific for LVSD¹; N-ANP, which reflects increased atrial pressure and distention and is part of the neurohumoral compensation to systolic dysfunction; and heart rate >diastolic blood pressure, which is a new, arbitrary index that presumably reflects the sympathetic nervous system's compensation for systolic dysfunction. They found that if abnormal ECG results alone are used for risk stratification, 60 of 120 echocardiograms would be avoided but at the cost of missing the diagnosis of LVSD in 1 patient. When echocardiography is done only in patients with abnormal ECG results and either an increased N-ANP or heart rate >diastolic pressure, 100 of 120 tests would be avoided but at the cost of missing the diagnosis in 4 patients. The study does not mention the clinical utility of echocardiography for determining the cause of LVSD or for assessing such concomitant disorders as valvular disease. Thus, withholding echocardiography in patients at lower risk for LVSD might avoid performance of a large number of tests giving negative results but would fail to reach the correct diagnosis in a substantial number of patients with LVSD. The next step in deciding on the optimal strategy is to do a controlled study of a larger number of patients and a cost benefit analysis.