PROGNOSTIC-SIGNIFICANCE OF SPECTRAL TURBULENCE ANALYSIS OF THE SIGNAL-AVERAGED ELECTROCARDIOGRAM IN PATIENTS WITH IDIOPATHIC DILATED CARDIOMYOPATHY

The aim of this study was to assess whether spectral turbulence analys is (STA) of the signal-averaged electrocardiogram (SAECG) is of progno stic use in patients with idiopathic dilated cardiomyopathy. SAECGs we re recorded at presentation in 84 patients with idiopathic dilated car diomyopathy and STA was performed using 183 Del Mar software. STA was abnormal (greater than or equal to 3 of the 4 standard parameters beyo nd the normal range) in 31 patients (37%). Patients were followed for a mean duration of 24 +/- 18 months (range 1 to 59) during which time 24 (29%) developed progressive heart failure (14 underwent cardiac tra nsplantation), 4 died suddenly or had aborted sudden death, and the ot hers remained clinically stable. Progressive heart failure occurred mo re often in patients who had an abnormal versus a normal STA result (1 5 [48%] vs 9 [17%]; p <0.002). Actuarial survival revealed a 1-year su rvival of 90% in patients with a normal STA result and 63% in patients with an abnormal STA result (9 <0.01). The predictive ability of STA to identify patients with progressive heart failure was sensitivity 63 %, specificity 77%, positive predictive value 54%, and negative predic tive value 83%. Univariate analysis identified peak oxygen consumption as having the largest relative risk for the development of progressiv e heart failure (9.55, 95% confidence interval [CI] 2.1 to 43.9). Left ventricular end-diastolic dimension (relative risk 4.18, 95% CI 1.5 t o 11.4) and STA (relative risk 3.81, 95% CI 1.7 to 8.8) were also sign ificantly associated with the development of progressive heart failure . Multivariate analysis showed that STA had a relative risk of 3.20 (9 5% CI 1.04 to 9.80). Abnormalities of the SAECG using STA are common i n patients with idiopathic dilated cardiomyopathy and are a noninvasiv e marker of patients at increased risk of developing progressive heart failure.