title: ECG features of microvolt T-wave alternans in coronary artery disease and long QT syndrome patients.
abstract: T-wave alternans (TWA) is a marker of myocardial electrical instability. We compared ECG features of microvolt TWA in coronary artery disease (CAD) and long QT syndrome (LQTS) patients.
  
  
  METHODS
  The study populations consisted of 43 CAD and 39 LQTS patients. TWA was detected in resting Holter recordings using the new correlation method (CM). After preprocessing to adjust for RR variability and respiratory modulation, CM was used to quantify TWA amplitude (A(CM)), duration (N(CM)), and magnitude (MAG(CM); defined as the product of A(CM) and N(CM)).
  
  
  RESULTS
  TWA was detected in 19 (44%) CAD and 17 (44%) LQTS patients. TWA was associated with longer RR intervals (P = 0.006) and had larger magnitudes (P = 0.067) in LQTS than CAD patients. The TWA was identified as transient (nonstationary) in 15 of 19 (79%) TWA-positive CAD patients, and in 8 of 17 (47%) TWA-positive LQTS patients (P = 0.047).
  
  
  CONCLUSIONS
  The frequency of TWA detected with CM is similar in LQTS and CAD patients. TWA is larger in LQTS than in CAD patients, whereas TWA is more frequently transient (nonstationary) in LAD than LQTS patients. In LQTS patients, but not in CAD patients, a longer RR is associated with TWA, indicating different electrophysiologic mechanisms in the two pathologies.
authors.affiliation: Department of Electrical Engineering, University of Rochester, New York 14642, USA.
authors.forename: L
authors.initials: L
authors.lastname: Burattini
authors.forename: W
authors.initials: W
authors.lastname: Zareba
authors.forename: E J
authors.initials: EJ
authors.lastname: Rashba
authors.forename: J P
authors.initials: JP
authors.lastname: Couderc
authors.forename: J
authors.initials: J
authors.lastname: Konecki
authors.forename: A J
authors.initials: AJ
authors.lastname: Moss
mesh_terms: D000328:Adult; D017023:Coronary Angiography; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005500:Follow-Up Studies; D006339:Heart Rate; D006801:Humans; D008133:Long QT Syndrome / Q000503:physiopathology*; D008875:Middle Aged; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted