Therapeutic Effects of Permanent Pacemaker in Patients With Sinus Node Dysfunction

Background: The electrocardiography (ECG) pattern of sinus node dysfunction (SND) does not always correlate with the symptoms. Objectives: The aim of this study was to find variables associated with therapeutic eects of permanent pacemaker in patients with sinus node dysfunction and abnormal electrophysiological findings. Methods: In this prospective study, 69 patients with symptomatic sinus node dysfunction and permanent pacemaker were selected from the Rajaie heart center in Tehran and Heshmat heart center in Rasht, Iran, between 2006 and 2015. Results: From a total of 69 patients enrolled in this study, 34 cases (49.3%) were females and the mean age of the patients was 63.2 9 years. Patients with the tachycardia-bradycardia syndrome were excluded from the study. The most frequent symptoms were weakness in 55 cases (79%) and dizziness in 52 (75%), and the least common symptoms were dyspnea in 27 cases (39%) and syncope in 9 cases (13%). There was no association between the type of symptoms and response to pacemaker. A non-invasive electrophysiological study (EPS) showed that 47 (68%) of the patients had CSNRT more than 783 ms. The mean age of the aforementioned patients was 66 5.43 years. There was a significant relationship between CSNRT more than 783 ms and symptom improvement 6 months after permanent pacemaker implantation (P = 0.000). Patients with exercise intolerance had better response to pacemaker compared to the patients with resting symptoms (P = 0.001). Mean age of the patients with CSNRT > 783 ms was significantly higher than those with CSNRT < 780 ms (66 5.43 years versus 56 11.50 years respectively, P = 0.001). Repolarization abnormalities did not correlate with persistence of clinical symptoms (P = 0.42). Conclusions: Pacemaker implantation can improve symptoms in sinus node dysfunction with corrected sinus node recovery time more than 783 ms. Symptoms related to the vagal nervous system can be the cause of persistence of clinical symptoms after pace- maker implantation.