Detecting Volume Responders prior to Implantation of a Cardiac Resynchronization Therapy Device via Minithoracotomy: The Septal Flash as a Predictor of Immediate Left Ventricular Reverse Remodeling

Abstract

Although cardiac resynchronization therapy (CRT) is well established as an adjunctive heart failure treatment, a 30% rate of nonresponders poses a challenge to improve the detection of potential responders prior to device implantation. A previously proposed mechanism-based approach to patient selection suggests in part that the septal flash is a sign of intraventricular dyssynchrony, which is predictive of CRT responsiveness. In this pilot study, data from 5 consecutive patients (2 women and 3 men; mean + or - SD age, 62 + or - 9 years) referred for CRT device implantation via a minithoracotomy were analyzed. Intraoperative transthoracic and/or transesophageal echocardiography data, as well as Doppler myocardial imaging data, were acquired before and after CRT device activation. The septal flash was defined as an early ventricular inward and outward septal motion within the isovolumic contraction period and was imaged with grayscale imaging or tissue Doppler color M-mode. Reverse remodeling was defined as a reduction in the left ventricular end-systolic volume (LVESV) of > or =10%. The right atrial and right ventricular leads were placed transvenously, and the LV screw-in lead was positioned epicardially on the lateral wall. The septal flash was detected preoperatively in all patients and resolved immediately after the onset of biventricular pacing. Immediately following pacemaker activation, we measured a significant reduction in the LVESV (248 + or - 99 mL versus 190 + or - 100 mL, P = .01) and an increase in the ejection fraction (19% + or - 5% versus 28% + or - 5%, P = .01) in all patients. Likewise, a significant increase in the postactivation dP/dt (rate of LV pressure change) measured noninvasively from the mitral regurgitation trace was noted in all patients (298.6 + or - 58.0 mm Hg/s versus 601.7 + or - 111.2 mm Hg/s, P = .001). The preoperative presence of the septal flash is a valid predictor of the response to CRT. Immediately after CRT device activation, the septal flash disappears, and LV reverse remodeling and an increase in contractility are observed.