Assessment of the Role of Speckle Tracking Echocardiography in Targeting the Left Ventricular Lead Position in Patients Undergoing Cardiac Resynchronization Therapy

Abstract

Heart failure is a complex clinical syndrome characterized by impaired myocardial performance and progressive activation of neuroendocrine system leading to circulatory insufficiency and congestion. Cardiac resynchronization therapy (CRT) is now a well-established treatment for patients with advanced heart failure. Apart from clinical benefits, improvement of left ventricular (LV) systolic function and LV reverse remodeling have been well-reported. Numerous studies have demonstrated the efficacy of CRT in treatment of patients with advanced heart failure. The rate of approximately 30% of inadequate responders worldwide remains an unsolved problem. One approach to improve outcome may be determination of the presence and degree of asynchrony before CRT as a predictor for CRT response. Conversely, the focus may be on an improved positioning of the left ventricular (LV) lead. To improve outcome and reduce the proportion of CRT non-responders, three different and complementary approaches have been proposed: optimization of patient selection; optimization of LV lead placement and optimization of the programming of the CRT device. The choice of the LV pacing site remains an important issue in patients requiring CRT. The importance of speckle tracking echocardiography (STE) in optimal LV pacing lead position was discussed in several studies comparing response to CRT in patients with the LV pacing lead at the segment/wall with the maximum mechanical delay to patients with the LV pacing lead at other segments. We aimed at our study to define the impact of speckle tracking echocardiography in determining the optimal LV pacing lead position as a method of CRT optimization. The current study was conducted on 50 patients with advanced congestive heart failure who had received CRT in Ain Shams University Hospitals in the period from 2013 to 2015. All patients were subjected to: thorough history taking with particular stress on age, gender, risk factors, symptoms including dyspnea were classified by New York Heart Association (NYHA) classification, and Minnesota living with heart failure questionnaire (MLHFQ). Also they underwent general and local examination including heart rate, blood pressure, body mass index (BMI). They were followed up 6 months after resynchronization. We made a detailed analysis of the 6 basal or mid segments of the LV in the short-axis parasternal view in terms of time to reach peak radial strain (positive value). Time to peak radial strain was determined for each wall in milliseconds in a parametric fashion enabled in the software and the latest wall was determined, the most delayed region was identified by having the two most delayed adjacent walls, then CRT was implanted blindly to our results and the patients were classified into two groups, (A) and (B): Group A: Patients were included in group A at baseline when they underwent CRT LV lead implantation in the coronary sinus vein tributary which corresponded to the latest contracting segm