The Effect of Left Cardiac Sympathetic Denervation on Exercise in Patients With Long QT Syndrome

OBJECTIVES This study evaluated the effect of left cardiac sympathetic denervation (LCSD) on heart rate, cardiac contractility, and cardiopulmonary fitness in human subjects. BACKGROUND The primary treatment for tong QT syndrome (LQTS) is beta-blacker (BB) therapy, but some patients experience breakthrough cardiac events or intolerable side effects. LCSD provides a significant antifibrillatory, protective effect in LQTS. However, the effect of LCSD on cardiopulmonary fitness in humans has not been previously described. METHODS A retrospective analysis of patients with LQTS and LCSD (2006 to 2017) who had both pre- and post-LCSD exercise stress tests (N = 55; 39 females; mean age at LCSD 22 +/- 12 years; mean follow-up 5.1 +/- 2.5 years; 36 patients with LQT1; 15 patients with LQT2). Forty patients (73%) were receiving BBs pre-LCSD. RESULTS Mean peak heart rate before LCSD was 143 +/- 23 beats/min, mean peak oxygen consumption (VO2) was 32 +/- 10 mt./kg/min, and mean peak respiratory exchange ratio was 1.14 +/- 0.12. There was no difference in peak heart rate, peak VO2, peak QTc, or respiratory exchange ratio pre- and post-LCSD. To evaluate the isolated effect of LCSD, the study performed a subset analysis of patients with LCSD monotherapy (n = 10) or no change in BB dose (n = 12). Patient-matched pre- and post-LCSD exercise testing showed no difference in heart rate, VO2, or left ventricular function following LCSD. CONCLUSIONS LCSD provides increased protection from an LQTS-triggered event without negatively affecting peak heart rate, cardiopulmonary fitness, or cardiac contractility, as assessed by both treadmill exercise stress testing and echocardiography. (C) 2019 by the American College of Cardiology Foundation.