title: Exercise-induced quantitative microvolt T-wave alternans in hypertrophic cardiomyopathy.
abstract: Patients with hypertrophic cardiomyopathy (HCM) have elevated risk for sudden cardiac death (SCD). Our study aimed to quantitatively characterize microvolt T-wave alternans (TWA), a potential arrhythmia risk stratification tool, in this HCM patient population.
  
  
  
  TWA was analyzed with the quantitative modified moving average (MMA) in 132 HCM patients undergoing treadmill exercise testing, grouped according to Maron score risk factors as high-risk (H-Risk, n=67,), or low-risk (L-Risk, n=65, without these risk factors).
  
  
  
  TWA levels were much higher for the H-Risk than for the L-Risk group (101.40±75.61 vs. 54.35±46.26μV; p<0.0001). A 53μV cut point, set by receiver operator characteristic (ROC), identified H-Risk patients (82% sensitivity, 69% specificity).
  
  
  
  High TWA levels were found for hypertrophic cardiomyopathy patients. Abnormal TWA associated with major risk factors for SCD: non-sustained ventricular tachycardia on Holter (p=0.001), family history of SCD (p=0.006), septal thickness ≥30mm (p<0.001); and inadequate blood pressure response to effort (p=0.04).
authors.affiliation: Clinical Unit of Cardiomyopathy and Aortic Diseases, Heart Institute (InCor) - Hospital das Clínicas da Faculdade de Medicina - Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Murillo
authors.initials: M
authors.lastname: de Oliveira Antunes
authors.affiliation: Clinical Unit of Electrocardiography, Heart Institute (InCor) - HC-FMUSP, São Paulo, Brazil.
authors.forename: Nelson
authors.initials: N
authors.lastname: Samesima
authors.affiliation: Clinical Unit of Electrocardiography, Heart Institute (InCor) - HC-FMUSP, São Paulo, Brazil.
authors.forename: Horacio Gomes
authors.initials: HG
authors.lastname: Pereira Filho
authors.affiliation: Clinical Unit of Cardiomyopathy and Aortic Diseases, Heart Institute (InCor) - Hospital das Clínicas da Faculdade de Medicina - Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Afonso Yoshikiro
authors.initials: AY
authors.lastname: Matsumoto
authors.affiliation: Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Verrier
authors.affiliation: Clinical Unit of Electrocardiography, Heart Institute (InCor) - HC-FMUSP, São Paulo, Brazil. Electronic address: ecg_pastore@incor.usp.br.
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Pastore
authors.affiliation: Hypertrophic Cardiomyopathy Department, Heart Institute (InCor) - HC-FMUSP, São Paulo, Brazil.
authors.forename: Edmundo
authors.initials: E
authors.lastname: Arteaga-Fernández
authors.affiliation: Clinical Unit of Cardiomyopathy and Aortic Diseases, Heart Institute (InCor) - Hospital das Clínicas da Faculdade de Medicina - Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Charles
authors.initials: C
authors.lastname: Mady
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000150:complications* / Q000175:diagnosis*; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000175:diagnosis*; D015716:Electrocardiography, Ambulatory / Q000379:methods*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity
keywords: Hypertrophic cardiomyopathy; T-wave alternans; Treadmill stress test