Clinical and echocardiographic correlates of elevated troponin in amyloid light-chain cardiac amyloidosis
Increased troponin is associated with poor survival in patients with amyloid light-chain (AL) amyloidosis with cardiac involvement (CAL). The purpose of this investigation was to define the relation between increased troponin and clinical, morphologic, and functional features. The comparative utility of clinical, echocardiographic, and biochemical measurements in predicting survival in CAL was also investigated. One hundred seventeen patients with CAL were divided into 2 groups: normal troponin I (<0.06 ng/ml, n = 42) or increased troponin I (≥0.06 ng/ml, n = 75). Patients in the high troponin I group were older (63 vs 58 years, p = 0.04), with higher B-type natriuretic peptide levels (1,417 vs 936 pg/ml, p = 0.0004). The high troponin I group also had higher echocardiography-determined early/late mitral inflow velocity ratio (2.2 vs 1.4, p = 0.005) and myocardial performance index (0.59 vs 0.45, p = 0.04) and lower stroke index (28 vs 38 ml/beat/m(2), p <0.0001) and left atrial systolic force (5.9 vs 8.4 k-dynes, p = 0.037) than the normal troponin group. Median survival was significantly shorter in the high troponin group (11 vs 45 months, p <0.001). At time of CAL diagnosis, univariate predictors of all-cause mortality included increased troponin, older age, male gender, New York Heart Association class III to IV, >2 organs involved, higher B-type natriuretic peptide, lower creatinine clearance, greater ventricular septal thickness, and higher myocardial performance index. However, by multivariate Cox survival analysis, only increased troponin was a significant predictor for all-cause mortality (hazard ratio 3.1, p = 0.002). In conclusion, increased troponin is associated with worse left ventricular and left atrial functions by echocardiography in patients with CAL. Among baseline variables, it is the strongest predictor of all-cause mortality in multivariate analysis. Troponin is a powerful tool in clinical and prognostic assessments of patients with CAL.