Acoustic cardiography augments prolonged QRS duration for detecting left ventricular dysfunction

Abstract

Background: Prolonged QRS duration has been used as a marker for left ventricular (LV) systolic dysfunction (SD) and is used in the evaluation of patients presenting with known or suspected heart failure. The goal of this study was to compare the abilities of QRS duration and simultaneous digital ECG and heart sounds, that is acoustic cardiographic, parameters to identify patients with LV dysfunction.

Methods: Our learning population consisted of 171 patients with possible chronic compensated or mildly decompensated heart failure who presented to an ambulatory cardiology clinic for echocardiographic examination. We defined LVSD as a LV ejection fraction < 50%, and estimated LV filling pressures from diastolic measurements. These patients also had acoustic cardiographic recordings from which we obtained a variety of individual ECG and acoustic cardiographic parameters. We used the product of four of these parameters to obtain a diagnostic score for LV dysfunction. We then compared the diagnostic performances of QRS duration and the score on a test population of patients who presented to an emergency department with possible heart failure.

Results: In the learning population, the sensitivities/specificities of QRS duration > or =120 ms and the score for prediction of LVSD were 51%/92% and 77%/90%, respectively. In the test population, the score remained superior to QRS duration for detecting LVSD as well as acute decompensated heart failure.

Conclusions: Improved identification of LVSD and clinical heart failure can be achieved with a cost-effective bedside screening tool with the simple combination of simultaneously acquired digital ECG and heart sound data.

Figure 1

Relationship of traditional systolic time intervals to acoustic cardiographic systolic parameters. Normal versus LVSD EMAT = electromechanical activation time; LA = left atrium; LV = left ventricle; LVET = left ventricular ejection time; LVST = left ventricular systolic time; PEP = preejection period.

Figure 2

ROC curves for detecting EF < 50% of QRS duration (AUC = 0.82). and multiplicative score (AUC = 0.89). Red star at QRS = 120 ms (Sensitivity 51%, Specificity 92%). Blue star at QRS = 100 ms (Sensitivity 86%, Specificity 59%). Abbreviations for Figure 1: AUC = area under the curve; EF = ejection fraction; MultScore = Multiplicative Score; QRSDUR = QRS duration; ROC = receiver operating characteristic.

Figure 3

ROC curves for detecting elevated LV filling pressure of QRS duration (AUC = 0.69). and multiplicative score (AUC = 0.84) Red star at QRS = 120 ms (Sensitivity 50%, Specificity 75%). Blue star at QRS = 100 ms (Sensitivity 81%, Specificity 40%). Abbreviations for Figure 1: AUC = area under the curve; LV = left ventricular; MultScore = Multiplicative Score; QRSDUR = QRS duration; ROC = receiver operating characteristic.

Figure 4

Log(QRS Duration) versus LVEF with red dots indicating those with elevated LV filling pressures (R squared = 0.30).

Figure 5

S3 strength (horizontal axis) versus E/A ratio (vertical axis) with red dots indicating those with elevated LV filling pressures.

Figure 6

QR interval versus IVRT with red dots indicating those with elevated LV filling pressures.

Figure 7

Multiplicative Score versus LVEF with red dots indicating high pressure. Vertical line indicating threshold on learning set for EF < 50%.