RESUMO
PURPOSE: Latency during left ventricle (LV) pacing has been suggested as a potential cause of ineffectual biventricular pacing. We assessed the incidence, predictors, and impact on outcome of increased LV latency in 274 patients undergoing cardiac resynchronization therapy (CRT). METHODS: On implantation, the latency interval was defined as the shortest stimulus-to-QRS onset interval in any lead of the 12-lead ECG. A stimulus-to-QRS onset interval ≥ 40 ms was used to define the presence of increased LV latency. RESULTS: Increased LV latency was observed in 55 patients (20%). On multivariate analysis, only ischemic etiology proved to be a predictor of increased LV latency. On 12-month echocardiographic evaluation, 68% patients showed a ≥ 15% decrease in LV end systolic volume (74% patients with increased LV latency, 67% patients without increased LV latency (p = 0.58). The presence of increased LV latency was not associated with a different clinical response to CRT. CONCLUSIONS: Increased LV latency occurred in almost 20% of patients undergoing CRT and was more frequent in patients with ischemic heart disease. The presence of increased LV latency does not seem to have an impact on echocardiographic or clinical response to CRT.
Assuntos
Estimulação Cardíaca Artificial/métodos , Eletrocardiografia , Insuficiência Cardíaca/terapia , Isquemia Miocárdica/terapia , Idoso , Análise de Variância , Estimulação Cardíaca Artificial/mortalidade , Terapia de Ressincronização Cardíaca/métodos , Terapia de Ressincronização Cardíaca/mortalidade , Estudos de Coortes , Ecocardiografia , Feminino , Insuficiência Cardíaca/diagnóstico por imagem , Insuficiência Cardíaca/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Isquemia Miocárdica/diagnóstico , Isquemia Miocárdica/mortalidade , Prognóstico , Estudos Prospectivos , Sistema de Registros , Medição de Risco , Índice de Gravidade de Doença , Taxa de Sobrevida , Resultado do Tratamento , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/terapiaRESUMO
PURPOSE: Identifying the left ventricular (LV) site associated with the maximum spontaneous interventricular conduction time (right ventricle (RV)-to-LV interval) has proved to be an effective strategy for optimal LV pacing site selection in cardiac resynchronization therapy (CRT). The aim of our study was to determine whether quadripolar LV lead technology allows RV-to-LV interval maximization. METHODS: We enrolled 108 patients undergoing implantation of a CRT system using an LV quadripolar lead and 114 patients who received a bipolar lead. On implantation, the RV-to-LV interval was measured for the dipole of the bipolar leads and for each electrode of the LV lead (tip, ring 2, ring 3, ring 4). RESULTS: In the quadripolar group, the mean RV-to-LV interval ranged from 90 ± 33 ms (tip) to 94 ± 32 ms (R4) (p > 0.05 for all comparisons). In 55 (51%) patients, the RV-to-LV interval was > 80 ms at all electrodes, while in 27 (25%) patients, no electrodes were associated with an RV-to-LV interval > 80 ms. At least one LV pacing electrode was associated with an RV-to-LV interval > 80 ms in 62 (70%) patients with a short (36 mm) inter-electrode distance, and in 19 (95%, p = 0.022) of those with a long distance (50.5 mm). In the bipolar group, the mean RV-to-LV interval was 72 ± 37 ms (p < 0.001 versus quadripolar). The RV-to-LV interval was > 80 ms in 44 (39%) patients (p < 0.001 versus quadripolar leads with both short and long inter-electrode distance). CONCLUSIONS: Quadripolar leads allow RV-to-LV interval maximization. An optimal RV-to-LV interval seems achievable in the majority of patients, especially if the leads present a long inter-electrode distance.