Should functional cardiac murmurs be diagnosed by auscultation or by Doppler echocardiography?

For many years, cardiac auscultation has been the only available method for distinguishing between functional and organic murmurs; however, a more reliable differential diagnosis can now be achieved with Doppler echocardiography. The question remains as to whether a Doppler echocardiogram needs to be routinely recorded in the presence of a heart murmur or whether the auscultatory diagnosis of a functional murmur is sufficient.

This prospective study attempts to answer this important question at a time when medical costs have to be curbed.

The three cardiologists involved in this study saw 516 new patients in their private practice over a 10-month period; of these, 321 (63.6%) underwent Doppler echocardiography. All patients underwent careful auscultation prior to echocardiography. At the end of their examinations, the cardiologists noted whether they considered the murmur to be of functional or organic origin. Minimal mitral or aortic regurgitations of short duration and low velocity occurring on non-thickened valves were considered functional.

The results for cardiac auscultation and Doppler echocardiography were considered to be concordant, that is, both techniques diagnosed either a functional or organic murmur in 250 of 321 patients (77.9%). The results for cardiac auscultation and Doppler echocardiography showed a major discordance in just six cases (1.9%). All were mitral regurgitations of moderate severity.

The prevalence of cardiac murmurs in the general population is very high. As echocardiography currently represents a significant proportion of cardiac medical expenditure, it would be wise to limit the use of this technique to essential indications. This study confirms that both cardiac auscultation and Doppler echocardiography possess important limitations. Nevertheless, it also shows that well-trained cardiologists can identify the vast majority of functional murmurs on auscultation. Better training of nonspecialist physicians in cardiac auscultation may help in containing medical expenses.