Development of an echocardiographic risk-stratification index to predict heart failure in patients with stable coronary artery disease: the Heart and Soul study

Abstract

Objectives: We sought to determine which transthoracic echocardiographic (TTE) measurements most strongly predict heart failure (HF) and to develop an index for risk stratification in outpatients with coronary artery disease (CAD).

Background: Many TTE measurements have been shown to be predictive of HF, and they might be useful if aggregated into a risk-prediction index.

Methods: We performed TTE in 1,024 outpatients with stable CAD enrolled in the Heart and Soul study and followed them for 4.4 years. With Cox proportional hazard models, we evaluated the association of 15 TTE measurements with subsequent HF hospital stay. Those measurements that independently predicted HF were combined into an index. Variables were defined as normal or abnormal on the basis of dichotomous cutoffs determined from the American Society of Echocardiography. Abnormal variables in each measurement were assigned points on the basis of strength of association with HF.

Results: Of the 15 variables, 5 measurements were independent predictors of HF: left ventricular mass index (LVMI), left atrial volume index (LAVI), mitral regurgitation (MR), left ventricular outflow tract velocity-time integral (VTI(LVOT)), and diastolic dysfunction (DD). In multivariate analysis, each of the 5 measurements independently predicted HF: LVMI >90 g/m(2) (hazard ratio [HR]: 4.1; 95% confidence interval [CI]: 2.3 to 7.2, p < 0.0001); pseudo-normal or restrictive DD (HR: 2.9; 95% CI: 1.8 to 4.5, p < 0.0001); VTI(LVOT) <22 mm (HR: 2.2; 95% CI: 1.4 to 3.5, p = 0.0004); mild, moderate, or severe MR (HR: 1.8; 95% CI: 1.2 to 2.8, p = 0.009); and LAVI >29 ml/m(2) (HR: 1.6; 95% CI: 1.0 to 2.5, p < 0.06). Combining these measurements, the Heart Failure Index ranged from 0 to 8, representing risk as follows: 3 points for LVMI, 2 points for DD, and 1 point for VTI(LVOT), MR, and LAVI. Among participants with 0 to 2 points: 4% had HF hospital stays (reference); 3 to 4 points: 10% (HR: 2.4; 95% CI: 1.3 to 4.4, p = 0.003); 5 to 6 points: 24% (HR: 6.2; 95% CI: 3.6 to 10.6, p < 0.0001); 7 to 8 points: 48% (HR: 13.7; 95% CI: 7.2 to 25.9, p < 0.0001).

Conclusions: We identified 5 TTE measurements that independently predict HF in patients with stable CAD and combined them as an index that might be useful for risk stratification and serial observations.

Figure 1. TTE Heart Failure Index: Risk Stratification of HF Hospital Stay by Score Increase in All 1,024 Patients

Transthoracic echocardiographic (TTE) Heart Failure Index predicts heart failure (HF) hospital stays in patients with stable coronary artery disease (CAD). The Heart Failure Index ranged from 0 to 8 points, representing risk as follows: 3 points for left ventricular mass index, 2 points for diastolic dysfunction, and 1 point for left ventricular outflow tract velocity-time integral, mitral regurgitation, and left atrial volume index. The graph shows risk stratification for HF hospital stay per increasing score on the index. This can be used to predict HF in patients with stable CAD. p < 0.05, adjusted for age, gender, body mass index, ejection fraction, renal insufficiency, history of heart failure, myocardial infarction, hypertension, and diabetes. *Number of participants hospitalized for HF/number with given TTE Heart Failure Index score. HR = hazard ratio.

Figure 2. TTE Heart Failure Index: Risk Stratification of HF Hospital Stay by Score Increase in 831 Patients Without History of HF at Baseline

The TTE Heart Failure Index predicts HF hospital stays in subgroup analysis of 831 patients with stable CAD and no history of HF. The Heart Failure Index ranged from 0 to 8 points, representing risk as follows: 3 points for LVMI; 2 points for diastolic dysfunction; and 1 point for left ventricular outflow tract velocity-time integral, mitral regurgitation, and left atrial volume index. The graph shows risk stratification for HF hospital stay per increasing score on the index. This can be used to predict incident HF in patients with stable CAD and no history of HF. p < 0.05. *Number of participants hospitalized for HF/number with given TTE Heart Failure Index score. Abbreviations as in Figure 1.

Figure 3. ROC for Congestive HF Hospital Stay Comparing the TTE Heart Failure Index Plus EF, NT-proBNP, and Age With EF and NT-proBNP Alone

The TTE Heart Failure Index can be an adjunct to age, left ventricular ejection fraction (LVEF), and N-terminal part of the pro-B-type natriuretic peptide (NT-proBNP) to predict HF, with the receiver operating characteristic (ROC) curve shown in the figure (c = 0.86). This was compared with the ROC curve of age, LVEF, and NT-proBNP (Model A, c = 0.84, p = 0.09). Abbreviations as in Figure 1.