Variáveis Ecocardiográficas Predizentes de Terapêuticas Apropriadas de Taquidisritmias Ventriculares em Doentes Submetidos a Terapêutica de Ressincronização Cardíaca Combinada

INTRODUCTION: The significant risk of sudden arrhythmic death in patients with congestive heart failure and electromechanical ventricular dyssynchrony has led to increased use of combined cardiac resynchronization therapy defibrillator (CRT-D) devices. OBJECTIVES: To evaluate the echocardiographic variables in patients undergoing CRT-D that predict the occurrence of appropriate therapies (AT) for ventricular tachyarrhythmia. METHODS: We analyzed 38 consecutive patients (mean age 60 +/- 12 years, 63% male) with echocardiographic evaluation before and 6 months after CRT-D implantation. Patients with AT were identified in a mean follow-up of 471 +/- 323 days. A standard echocardiographic study was performed including tissue Doppler imaging (TDI). Responders were defined as patients with improvement in NYHA class of < or = 1 in the first six months, and reverse remodeling as a decrease in left ventricular end-systolic volume of < or = 15% and/or an increase in left ventricular ejection fraction of > 25%. RESULTS: The responder rate was 74%, and the reverse remodeling rate was 55%. AT occurred in 21% of patients, who presented with greater left ventricular end-diastolic internal diameter (LVEDD) before implantation (86 +/- 8 vs. 76 +/- 11 mm, p = 0.03) and at 6 months (81 +/- 8 vs. 72 +/- 14 mm, p = 0.08), and increased left ventricular end-systolic internal diameter (66 +/- 14 vs. 56 +/- 14 mm, p = 0.03) and lower ejection fraction (24 +/- 6 vs. 34 +/- 14%, p = 0.08) at 6 months. In the group with AT, the responder rate was lower (38 vs. 83%, p = 0.03), without significant differences in reverse remodeling (38% for the AT group vs. 60%, p = 0.426) or in the other variables. By univariate analysis, predictors of AT were LVEDD before implantation and E' after implantation. Age, gender, ischemic etiology, use of antiarrhythmic drugs, reverse remodeling and the other echocardiographic parameters did not predict AT. In multivariate logistic regression analysis, both LVEDD before implantation (OR 1.24, 95% CI 1.04-1.48, p = 0.019) and postimplantation E' (OR 0.27, 95% CI 0.09-0.76, p = 0.014) remained as independent predictors of AT. CONCLUSIONS: In patients undergoing CRT-D, episodes of ventricular tachyarrhythmia occur with high incidence, independently of echocardiographic response, with LVEDD before implantation and E' after implantation as the only independent predictors of AT in the medium-term. These results highlight the importance of combined devices with defibrillation capability.

Utilidade do Doppler Tecidular na Predição de Eventos Arrítmicos em Adultos com Tetralogia de Fallot Corrigida

INTRODUCTION: Adults with repaired tetralogy of Fallot (TOF) may be at risk for progressive right ventricular (RV) dilatation and dysfunction, which is commonly associated with arrhythmic events. In frequently volume-overloaded patients with congenital heart disease, tissue Doppler imaging (TDI) is particularly useful for assessing RV function. However, it is not known whether RV TDI can predict outcome in this population. OBJECTIVE: To evaluate whether RV TDI parameters are associated with supraventricular arrhythmic events in adults with repaired TOF. METHODS: We studied 40 consecutive patients with repaired TOF (mean age 35 +/- 11 years, 62% male) referred for routine echocardiographic exam between 2007 and 2008. The following echocardiographic measurements were obtained: left ventricular (LV) ejection fraction, LV end-systolic volume, LV end-diastolic volume, RV fractional area change, RV end-systolic area, RV end-diastolic area, left and right atrial volumes, mitral E and A velocities, RV myocardial performance index (Tei index), tricuspid annular plane systolic excursion (TAPSE), myocardial isovolumic acceleration (IVA), pulmonary regurgitation color flow area, TDI basal lateral, septal and RV lateral peak diastolic and systolic annular velocities (E' 1, A' 1, S' 1, E' s, A' s, S' s, E' rv, A' rv, S' rv), strain, strain rate and tissue tracking of the same segments. QRS duration on resting ECG, total duration of Bruce treadmill exercise stress test and presence of exercise-induced arrhythmias were also analyzed. The patients were subsequently divided into two groups: Group 1--12 patients with previous documented supraventricular arrhythmias (atrial tachycardia, fibrillation or flutter) and Group 2 (control group)--28 patients with no previous arrhythmic events. Univariate and multivariate analysis was used to assess the statistical association between the studied parameters and arrhythmic events. RESULTS: Patients with previous events were older (41 +/- 14 vs. 31 +/- 6 years, p = 0.005), had wider QRS (173 +/- 20 vs. 140 +/- 32 ms, p = 0.01) and lower maximum heart rate on treadmill stress testing (69 +/- 35 vs. 92 +/- 9%, p = 0.03). All patients were in NYHA class I or II. Clinical characteristics including age at corrective surgery, previous palliative surgery and residual defects did not differ significantly between the two groups. Left and right cardiac chamber dimensions and ventricular and valvular function as evaluated by conventional Doppler parameters were also not significantly different. Right ventricular strain and strain rate were similar between the groups. However, right ventricular myocardial TDI systolic (Sa: 5.4+2 vs. 8.5 +/- 3, p = 0.004) and diastolic indices and velocities (Ea, Aa, septal E/Ea, and RV free wall tissue tracking) were significantly reduced in patients with arrhythmias compared to the control group. Multivariate linear regression analysis identified RV early diastolic velocity as the sole variable independently associated with arrhythmic history (RV Ea: 4.5 +/- 1 vs. 6.7 +/- 2 cm/s, p = 0.01). A cut-off for RV Ea of < 6.1 cm/s identified patients in the arrhythmic group with 86% sensitivity and 59% specificity (AUC = 0.8). CONCLUSIONS: Our results suggest that TDI may detect RV dysfunction in patients with apparently normal function as assessed by conventional echocardiographic parameters. Reduction in RV early diastolic velocity appears to be an early abnormality and is associated with occurrence of arrhythmic events. TDI may be useful in risk stratification of patients with repaired tetralogy of Fallot.