title: Microvolt T-wave alternans in adults with complex congenital heart diseases.
abstract: BACKGROUND
  Sudden cardiac death (SCD) mostly resulting from ventricular arrhythmia remains a cause of mortality in 19-30% of adults with congenital heart defects. Indications for implantable cardioverter-defibrillators in primary prophylaxis are still under research. MicrovoltT wave alternans (MTWA) is one of the SCD risk stratification methods. We determined the incidence of MTWA in these patients and its coincidence with ventricular arrhythmia, as well as risk factors of ventricular arrhythmia/SCD.
  
  
  METHODS
  204 patients with complex congenital heart anomalies and 45 healthy volunteers underwent ambulatory ECG monitoring, a cardiopulmonary test, B-type natriuretic peptide assessment, echocardiography and an MTWA test. After excluding technically inadequate traces, the remaining 179 patients and 43 controls were classified into MTWA positive (+), negative (-) and indeterminate (ind) subgroups. Additionally, MTWA (+) and MTWA (ind) formed an 'abnormal' group, labeled MTWA (non-).
  
  
  RESULTS
  Abnormal MTWA was observed more frequently in the study group compared to controls (59 [33.0%] vs. 1 [2.3%], p = 0.000001). The MTWA (non-) group compared to MTWA (-) presented a higher number of males (61.0% vs. 37.5%, p = 0.005), predominance of patients with NYHA > I (44.1% vs. 25.0%, p = 0.007), pulmonary hypertension (16.9% vs. 0.8%, p = 0.00007), lower blood saturation (97% [73-100] vs. 99% [69-100], p = 0.0003), higher incidence of malignant arrhythmia (9 [15.2%] vs. 3 [2.5%], p = 0.003), lower peak oxygen consumption VO2 [mL/kg/min] (23.1 ± 5.9 vs. 26.3 ± 6.7, p = 0.002), higher VE//VCO2 slope (36.0 [25-74] vs. 31.0 [21-58], p = 0.01). Multivariate logistic regression analysis proved that pulmonary hypertension (OR = 13.7, p = 0.03), male gender (OR = 10.4,p = 0.00002), VE/VCO2 slope (OR = 1.07, p = 0.045) and VO2 (OR = 0.89, p = 0.04) increase the probability of MTWA (non-).
  
  
  CONCLUSIONS
  Abnormal MTWA is more frequent in adults with congenital heart diseases than in the healthy population. Its probability increases in patients demonstrating clinical findings conducive to lethal arrhythmia like heart failure and pulmonary hypertension.
authors.forename: Olga
authors.initials: O
authors.lastname: Trojnarska
authors.affiliation: University of Medical Sciences, Poznan. ola.cieplucha@gmail.com.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Ciepłucha
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Bartczak
authors.forename: Lucyna
authors.initials: L
authors.lastname: Kramer
authors.forename: Stefan
authors.initials: S
authors.lastname: Grajek
mesh_terms: D000200:Action Potentials; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D015897:Comorbidity; D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D015716:Electrocardiography, Ambulatory; D005080:Exercise Test; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006330:Heart Defects, Congenital / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality; D006339:Heart Rate; D006801:Humans; D006976:Hypertension, Pulmonary / Q000453:epidemiology; D015994:Incidence; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020097:Natriuretic Peptide, Brain / Q000097:blood; D016017:Odds Ratio; D010101:Oxygen Consumption; D011044:Poland / Q000453:epidemiology; D018570:Risk Assessment; D012307:Risk Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D020097:Natriuretic Peptide, Brain