Microvolt T-Wave Alternans and the Risk of Death or Sustained Ventricular Arrhythmias in Patients With Left Ventricular Dysfunction

• Published in: Journal of the American College of Cardiology Vol. 47; no. 2; pp. 456 - 463
• Main Authors: Bloomfield, Daniel M., Bigger, J. Thomas, Steinman, Richard C., Namerow, Pearila B., Parides, Michael K., Curtis, Anne B., Kaufman, Elizabeth S., Davidenko, Jorge M., Shinn, Timothy S., Fontaine, John M.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 17-01-2006; Elsevier Science; Elsevier Limited
• Subjects: Arrhythmias, Cardiac - epidemiology; Arrhythmias, Cardiac - prevention & control; Biological and medical sciences; Cardiac arrhythmia; Cardiac dysrhythmias; Cardiology; Cardiology. Vascular system; Cardiomyopathy; Cardiovascular disease; Confidence intervals; Defibrillators, Implantable; Electrocardiography; Family medical history; Female; Fitness equipment; Heart; Heart attacks; Heart failure; Heart failure, cardiogenic pulmonary edema, cardiac enlargement; Heart rate; Humans; Male; Medical prognosis; Medical sciences; Middle Aged; Mortality; Patient Selection; Prognosis; Risk Assessment; Studies; Treatment Outcome; Ventricular Dysfunction, Left - epidemiology; MADIT; NYHA; MTWA; CI; CMS; LVEF; ICD; SCD-HeFT; Human; Arrhythmia; Cardiovascular disease; Risk; Heart ventricle; Left ventricular failure; Phlebology; T wave; Heart disease; Risk factor; Death; Circulatory system; Cardiology; Left ventricle performance
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/j.jacc.2005.11.026

Microvolt T-Wave Alternans and the Risk of Death or Sustained Ventricular Arrhythmias in Patients With Left Ventricular Dysfunction
Daniel M. Bloomfield, J. Thomas Bigger, Richard C. Steinman, Pearila B. Namerow, Michael K. Parides, Anne B. Curtis, Elizabeth S. Kaufman, Jorge M. Davidenko, Timothy S. Shinn, John M. Fontaine
We studied 549 patients with either ischemic or non-ischemic heart disease and left ventricular ejection fraction ≤0.40. Patients with an abnormal microvolt T-wave alternans (MTWA) test were 6.5 times more likely to die or experience a non-fatal sustained ventricular arrhythmia than patients with a normal test who only had a 2.5% two-year event rate. The MTWA can help identify patients with left ventricular dysfunction who are unlikely to benefit from implantable cardioverter-defibrillator prophylaxis.
This study hypothesized that microvolt T-wave alternans (MTWA) improves selection of patients for implantable cardioverter-defibrillator (ICD) prophylaxis, especially by identifying patients who are not likely to benefit.
Many patients with left ventricular dysfunction are now eligible for prophylactic ICDs, but most eligible patients do not benefit; MTWA testing has been proposed to improve patient selection.
Our study was conducted at 11 clinical centers in the U.S. Patients were eligible if they had a left ventricular ejection fraction (LVEF) ≤0.40 and lacked a history of sustained ventricular arrhythmias; patients were excluded for atrial fibrillation, unstable coronary artery disease, or New York Heart Association functional class IV heart failure. Participants underwent an MTWA test and then were followed for about two years. The primary outcome was all-cause mortality or non-fatal sustained ventricular arrhythmias.
Ischemic heart disease was present in 49%, mean LVEF was 0.25, and 66% had an abnormal MTWA test. During 20 ± 6 months of follow-up, 51 end points (40 deaths and 11 non-fatal sustained ventricular arrhythmias) occurred. Comparing patients with normal and abnormal MTWA tests, the hazard ratio for the primary end point was 6.5 at two years (95% confidence interval 2.4 to 18.1, p < 0.001). Survival of patients with normal MTWA tests was 97.5% at two years. The strong association between MTWA and the primary end point was similar in all subgroups tested.
Among patients with heart disease and LVEF ≤0.40, MTWA can identify not only a high-risk group, but also a low-risk group unlikely to benefit from ICD prophylaxis.