Ecocardiografía con speckle trackingutilidad pronóstica de la formación miocárdica en pacientes candidatos a terapia de resincronización cardiaca

Abstract

Background and objectives. Cardiac resynchronization therapy (CRT) improves survival in patients with symptomatic heart failure (HF), reduced left ventricular ejection fraction and prolonged QRS duration. A favorable response to CRT is determined by multiple factors. Novel echocardiographic parameters of myocardial strain account for global LV systolic chamber function, and may therefore have additional prognostic value to conventional prognostic factors. Methods. A cohort of 231 consecutive symptomatic HF patients referred for CRT implant was studied, all with QRS ≥120 ms and LV ejection fraction (LVEF) ≤35%. Global longitudinal strain (GLS) and global circumferential strain (GCS) were determined by speckle tracking echocardiography prior to CRT implant. A value of ≤-9% indicated those patients with better contractile function. A favorable echocardiographic response was defined as a reduction in LV end-systolic volume ≥15% from baseline at 6 months of follow-up. Clinical response at 4 years of follow-up was evaluated, according to the primary clinical end-point of death, transplant or LV assist device implantation and the secondary clinical end-points of death and HF hospitalization, and the occurrence of ventricular arrhythmic events. Results. There were 105 patients (45%) with GLS ≤−9% and 81 patients (31%) with GCS ≤−9%. 55% of the patients were echocardiographic responders at 6 months. Baseline GLS and GCS were significantly associated to echocardiographic response, odds ratio for GLS 1.17 (95% CI: 1.05-1.29, p=0.004); odds ratio for GCS 1.33 (95% CI: 1.14-1.55, p<0.001). At the end of the follow-up period, 87 patients had reached the primary clinical end-point, and 118 reached the secondary end-point. 41 patients suffered of ventricular arrhythmias during the first 2 years of follow-up. A strain value >-9% was significantly associated with the primary and secondary end-points, and with the combined end-point of death and ventricular arrhythmias. Baseline global strain measures showed additive prognostic value to routine clinical, electrocardiographic or echocardiographic parameters in the survival models, p<0.001. Prognostic value of global strain remained significantly associated to outcomes in the subgroup analysis according to HF etiology (ischemic and non-ischemic), as well as in the group of electrocardiographic intermediate criteria (QRS width 120 - 149 ms or non–left bundle branch block). Conclusions. GLS and GCS measures derived from echocardiographic speckle tracking analysis are of value to predict echocardiographic and clinical response in patients receiving CRT, and provide additional prognostic value. Therefore, this technique should be incorporated in the clinical decision making process of those patients referred for CRT.