RESUMO
<p><b>OBJECTIVE</b>To explore the predict value of microvolt level T-wave alternans (MTWA) for malignant ventricular arrhythmia (MVA) and sudden cardiac death (SCD) in high risk patients.</p><p><b>METHODS</b>A total of 105 healthy subjects (control group) and 138 patients with history of VT or VF or patients with LVEF < or = 45% (SCD high risk group) were included in this study (mean age 52 years old). MTWA, LVEF, HRV, NSVT, QRS, QTc values and MACE data (death, causes of death, MVA, re-hospitalization, syncope) during follow up (12.0 +/- 1.3) months were obtained.</p><p><b>RESULTS</b>The normal reference value of MTWA was defined as < 37 microV. Positive rate in SCD high risk group was significantly higher than that in control group (45.7% vs. 4.8%, P < 0.01). There was no cardiovascular event report in control group. In SCD high risk group, there were 11 deaths (MTWA positive rate 81.8%) including 7 SCD (MTWA positive rate 85.7%), 17 MVA (MTWA positive rate 88.2%), 9 cases of syncope (MTWA positive rate 77.8%), 21 cases of re-hospitalization during the follow up (MTWA positive rate 85.7%). Logistic regression analysis revealed that positive MTWA, a history of myocardial infarction and LVDd > or = 60 mm were risk factors for all cause of death and positive MTWA was the only factor to predict SCD. The factors related to MVA in turn were positive MTWA, LVEF < or = 35%, a history of cardiopulmonary resuscitation and a history of syncope. Positive MTWA and LVEF < or = 35% are the independent risk factors for predicting MVA (P < 0.01). The sensitivity was 91% and specifity was 66% by combined use of positive MTWA and LVEF < or = 35% to predict MVA. MTWA positive rates were 68.3% and 87.5% respectively in 41 ICD patients and ICD patients with automatic shock during follow up.</p><p><b>CONCLUSION</b>Non-invasive MTWA measurement could be used as a screening tool to predict SCD or MVA in high risk patients.</p>