Long-term outcomes in patients with abnormal microvolt T wave Alternans

Authors:
K. Tanno¹, H. Ito¹, T. Onuki¹, Y. Minoura¹, M. Kawamura¹, T. Asano¹, Y. Kobayashi¹, ¹Showa University - Tokyo - Japan,

Topic(s):
Non invasive studies

Citation:
European Heart Journal ( 2007 ) 28 ( Abstract Supplement ), 408

Although patients with negative microvolt T wave Alternans (MTWA) has been considered to be better outcomes than patients with abnormal (positive or indeterminate) MTWA, long-term outcomes in patients with abnormal MTWA is not clear.

Methods: The subject was the patients who underwent MTWA test from January, 1998 to July, 2004. The Number of patients was 1891, mean age:60±15, female/male: 452/1439. Of 1891 patients, 926 patients had ischemic heart disease (IHD), 407 patients had non-ischemic heart disease (non-IHD) and the remaining 558 patient had no obvious structural heart disease. MTWA recordings were made with the CH2000 system (Cambridge Heart, Inc. Bedford, MA) using atrial pacing, exercise or isoproterenol to increase heart rate. MTWA was considered positive when alternans voltage was more than 1.9 microvolt and the alternans ratio was greater than 3 for more than 1 minute in VM, X, Y, Z, or two adjacent precordial leads without artifact at a heart rate of less than 110 bpm. MTWA was considered negative if there was no significant alternans for 1 minute while the heart rate was greater than 100 bpm, or if the tracing was not obscured by noise or ectopic beats. Otherwise, MTWA was considered indeterminate. The date of the MTWA test was regarded as day 1 of the study, and patients were followed up prospectively at our university hospital outpatient clinic every one or two month.

Results: During a mean follow-up periods of 54±29 months, 1816 of 1891 patients could be followed up their clinical course. In 1816 patients, 63 patients died of cardiac disease and 72 patients died of non-cardiac disease. Kaplan-Meier analysis revealed that the total mortality in patients with negative MTWA was significantly lower than that of patients with abnormal MTWA (p<0.01). In patients with IHD, 12 patients died suddenly. Of whom, one patient was positive MTWA, 3 patients were negative MTWA and 8 patients were indeterminate MTWA. Ventricular tachycardia (VT) was documented in 73 patients, in whom 40 patients was positive MTWA, 12 patients was negative MTWA and 21 patients was indeterminate MTWA. In patients with non-IHD, 8 patients was sudden cardiac death (SCD), of whom 6 patients were positive MTWA and 2 patients were negative MTWA. Fifty-four patients suffered from VT, of whom 40 patients were positive MTWA and 4 patients were negative MTWA.

Conclusion: This study suggested that negative MTWA was associated with better prognosis than abnormal MTWA even in long-term follow-up. In patients with IHD, positive MTWA was related to VT, not SCD, while positive MTWA was related to VT and SCD in patient with non-IHD.