title: T-wave alternans in apparently healthy subjects and in different subsets of patients with ischaemic heart disease.
abstract: OBJECTIVE
  Microvolt T-wave alternans (TWA) predicts arrhythmic risk in patients with ischaemic heart disease (IHD). While TWA has widely been assessed by the spectral method, it has been poorly characterized in healthy people as well as in IHD patients by the modified moving average (MMA) method.
  
  
  RESULTS
  We enrolled 729 consecutive subjects, referred for exercise stress test (EST). T-wave alternans was assessed by the MMA method, considering all 12 electrocardiogram (ECG) leads (TWA_tot) or the 6 ECG pre-cordial leads only (TWA_prec). Patients were divided into five groups: (i) no history of IHD and normal EST (Group 1); (ii) no history of IHD but positive EST (Group 2); (iii) ischaemic heart disease without any acute myocardial infarction [AMI (Group 3)]; (iv) old AMI (Group 4); (v) recent AMI (Group 5). T-wave alternans values >95th percentile of those measured in Group 1 were considered 'abnormal'. The 95th percentile of TWA values in Group 1 was 75 µV for TWA_tot and 65 µV for TWA_prec. T-wave alternans values and prevalence of abnormal TWA increased from Groups 1-2 to Group 5 (P< 0.00001 for both). Group 4 and Group 5, compared with Group 1, showed a significant higher prevalence of abnormal values of TWA_tot [odds ratio (OR) 1.70 (P= 0.002), and 2.07 (P= 0.01), respectively] and TWA_prec [OR 1.51 (P= 0.02) and 2.37 (P= 0.003), respectively] at multivariable analysis. In IHD patients EST-induced ischaemia did not influence TWA; in AMI patients, impaired left ventricular function was associated with higher TWA values.
  
  
  CONCLUSIONS
  In healthy people, TWA_tot and TWA_prec were ≤75 and ≤65 µV, respectively, in 95% of subjects. In IHD patients TWA values were higher compared with healthy individuals; a history of AMI was independently associated with abnormal TWA values.
authors: Department of Cardiovascular Medicine,  Università Cattolica del Sacro Cuore, Rome,  Italy.
authors: Roberto
authors: R
authors: Mollo
authors: Alessandro
authors: A
authors: Cosenza
authors: Antonella
authors: A
authors: Spinelli
authors: Ilaria
authors: I
authors: Coviello
authors: Giulia
authors: G
authors: Careri
authors: Irma
authors: I
authors: Battipaglia
authors: Marianna
authors: M
authors: Laurito
authors: Gaetano
authors: G
authors: Pinnacchio
authors: Gaetano A
authors: GA
authors: Lanza
authors: Filippo
authors: F
authors: Crea
mesh_terms: D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000453:epidemiology*; D015897:Comorbidity; D004562:Electrocardiography / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000453:epidemiology*; D015995:Prevalence; D018570:Risk Assessment; D012307:Risk Factors