Abstract 3817: Audibility of the Fourth Heart Sound Correlates with the Level of Left Ventricular Diastolic Function
Background: The correlation of the fourth heart sound (S4) with abnormal left ventricular (LV) compliance is based on studies using age > 65 years and clinical evidence of heart disease as indicators of LV diastolic dysfunction.
Methods: To examine this correlation with less chance of misclassification, auscultation, with the stethescope bell positioned at the cardiac apex and with the subject in the left lateral decubitus position, was performed by 3 independent examiners, blinded to the subjects’ diastolic function, on 50 males and 56 females in sinus rhythm who had just completed standardized echocardiographic and Doppler examinations for clinical indications and who did not have other entities which could cause adventitial heart sounds (interventricular conduction delay >100 msec, AV block >220 msec, pacemaker, prosthetic valves, severe mitral regurgitation, AV shunt, anemia, or thyrotoxicosis). Any double heart sound immediately prior to the carotid upstroke was considered to be an S4. Auscultation was repeated the next day in 9 subjects. Diastolic function was classified by consensus of 3 interpreters, blinded to auscultation results, using standard criteria of Doppler measurments of mitral in-flow, mitral annulus motion and pulmonary vein flow. Based on Doppler classification of normal vs abnormal diastolic function, the S4 sensitivity was 43%, specificity 65%, and accuracy 53%. Accuracy among individual auscultators was: student 49%, resident 54%, and attending 43% (with the most false-positives). Inter-rater (kappa=0.32)and intra-rater (kappa 0.54) agreement was good (both p<0.004).
Conclusions: The S4 is a poor indicator of LV diastolic dysfunction. Indeed, it is absent in those with severe dysfunction, where late diastolic flow, due to atrial systole, is diminished relative to passive filling in early diastole.