Table 3.
Main studies evaluating the role of microvolt T-wave alternans in predicting arrhythmic and non arrhythmic events
| Ref. | Clinical setting | Number of patients | Parameter evaluated | End-points (mean follow-up) | Results |
| Adachi et al[56], 1999 | NIDCM | 57 | TWA, LVEF, NYHA, Signal average ECG, QT dispersion | Ventricular tachycardia | MTWA associated with VT |
| Klingenheben et al[57], 2000 | CHF (no history SVT/VF) | 107 | TWA | Arrhythmic events (follow-up 18 mo) | MTWA is an independent predictor of arrhythmic events |
| Kitamura et al[58], 2002 | NIDCM | 146 | Onset heart rate for TWA | SCD, documented sustained ventricular tachycardia/ventricular fibrillation (follow-up 21 ± 14 mo) | TWA and LVEF were independent predictors of arrhythmic events |
| Hohnloser et al[59], 2003 | NIDCM (LVEF 29 ± 11%) | 137 | MTWA, FEVS, mean RR interval, HRV, BRS. | SCD, SCA, SVT or VF (follow-up 14 ± 6 mo) | MTWA is an independent predictor of ventricular tachyarrhythmic events |
| Bloomfield et al[60], 2004 | IDCM (LVEF ≤ 30%) | 177 | MTWA, QRS measurement | All-cause mortality. (follow-up 20 ± 6 mo) | Compared to QRS duration, an abnormal MTWA is a stronger predictor of death |
| Salerno-Uriate et al[61], 2007 | NIDCM (NYHA II-III LVEF ≤ 40%) | 446 | TWA, VO2 peak | Combined primary endpoint of cardiac death and life-threatening ventricular arrhythmias Secondary endpoint: total mortality, combination of arrhythmic death and life-threatening arrhythmias. (follow-up 18 to 24 mo) | Abnormal TWA associated with a 4-fold higher risk of cardiac death and life-threatening arrhythmias |
| Baravelli et al[62], 2007 | NIDCM (NYHA II-III LVEF 29 ± 6.4%) | 70 | MTWA, VO2 peak | Combined primary endpoint of MCE: total cardiac death or VT/VF (including appropriate ICD shock) Secondary endpoint: MAE: SCD or SVT/VF (follow-up 19.2 ± 10.7 mo) | MTWA and peak VO2, but not the two single tests, were significant prognostic markers of both MCE and MA |
| Gold et al[63], 2008 | CHF (IDCM/NIDCM, 71% NYHA II, LVEF 24 ± 7%) | 490 | TWA | Composite primary end point: SCD, SVT / VF, or appropriate ICD discharge (follow-up 30 mo) | MTWA not predictive of MAE or mortality |
| Costantini et al[64], 2009 | IDCM LVEF ≤ 40% | 566 | TWA, EPS | Primary endpoint: appropriate ICD discharge or SCD at 1 yr follow-up (follow-up 1.6 ± 0.6 yr) | Strategies employing MTWA, EPS, or both might identify the subset of patients least likely to benefit from ICD implantation |
BRS: Baroreflex sensitivity; CHF: Chronic heart failure; EPS: Electrophysiological study; HR: Heart rate; HRV: Heart rate variability; ICD: Implantable cardioverter defibrillator; LVEF: Left ventricular ejection fraction; MCE: Major cardiac events; MTWA: Microvolt T-Wave alternans; NYHA: New York Heart Association; NSVT: Non sustained ventricular tachycardia; OHR: Onset heart rate; SR: Sinus rhythm; SCA: Sudden cardiac arrest; SCD: Sudden cardiac death; SDNN: Standard deviation of RR intervals; VF: Ventricular fibrillation; VT: Ventricular tachycardia.