Microvolt T-wave alternans in adults with congenital heart diseases

Abstract

Purpose: Sudden cardiac death (SCD) in adults with congenital heart diseases (CHD) is usually caused by ventricular arrhythmia (VA). Microvolt T-wave alternans (MTWA) proved its role in SCD risk stratification. Aim of study: Evaluation of spectral MTWA incidence in patients (P) with CHD and determination its association with VA and potential risk factors of SCD. Methods: Study group: 204P (93men), aged 33,8±11,4years with CHD (TGA, UVH, Ebstein's anomaly, ccTGA, Eisenmenger syndrome, DORV, CAT, unoperated and operated ToF) underwent MTWA, ECG, 24h Holter ECG, BNP assessment and cardiopulmonary exercise test. Control group: 45 adults age- and sex-matched. MTWA classification: normal: negative (-) and abnormal: positive (+) and indeterminate (ind). Due to similar prognostic significance tests classified as MTWA(+) and MTWA(ind) were combined into non-negative(non-) group. VA classification: malignant- sustained ventricular tachycardia (sVT), potentially malignant- non-sustained ventricular tachycardia (nsVT) and >10 premature ventricular complexes per hour (PVC/h). Results: 31P were MTWA(+), 53P MTWA(ind) and 120P MTWA(-). Due to excessive noise 25P were excluded. MTWA(non-) was more frequent in study group vs. controls (p=0,000001). The highest ratio of MTWA(non-) was in Eisenmenger syndrome (87,5%). Among patients with MTWA(non-) malignant and potentially malignant VA was more frequent compared to MTWA(-) (p=0,003; p=0,016, respectively). Male gender and pulmonary hypertension (PH) were more often in MTWA(non-) vs. MTWA(-) (p=0,0049; p=0,00007, respectively). MTWA(non-) compared to MTWA(-) had lower: blood saturation (p=0,000295), maximal oxygen consumption (peakVO2) (p=0,002) and VE/VCO2slope (p=0,012). MTWA(non-) vs. MTWA(-) had higher: BNP values (p=0,0306) and NYHA class (p=0,007). Factors increasing MTWA(non-) incidence are: in univariate logistic regression: PH (OR=24,29), sVT (OR=7,31), VA (OR=3,01), male gender (OR=2,61), NYHA>I (OR=2,06), worse VE/VCO2slope (OR=1,07) and peakVO2 fall (OR=0,92); in multivariate logistic regression: PH (OR=14,16), male gender (OR=10,2), worse VE/VCO2slope (OR=1,06) and peakVO2 fall (OR=0,89). Conclusions: In adults with CHD abnormal MTWA occurs more often than in healthy population. Probability of this phenomenon increases in patients with malignant ventricular arrhythmia and clinical findings possibly related to lethal arrhythmia including advanced heart failure and pulmonary hypertension. Incidence of abnormal MTWA is higher in men. MTWA might be of potential role in SCD risk stratification in adults with congenital heart diseases.