Long‐Term Performance of Coronary Sinus Leads Used for Cardiac Resynchronization Therapy

BACKGROUND: Little is known regarding the long-term performance of coronary sinus (CS) leads, which have an effect on the longevity of cardiac resynchronization therapy (CRT) systems. METHODS: This study included 109 patients (79 men) whose mean age was 68 +/- 9 years, New York Heart Association (NYHA) functional class 3.2 +/- 0.5, and left ventricular ejection fraction 25.6 +/- 6.6%, and who underwent CRT (n = 45) or CRT-D (n = 64) systems implants for management of idiopathic (53%), ischemic (40%), or miscellaneous (7%) dilated cardiomyopathy. Unipolar (n = 57) or bipolar (n = 52) leads were placed into the CS venous system. RESULTS: At implant, no significant difference was observed between unipolar and bipolar leads with respect to mean sensing performance (14 +/- 6 mV vs 14 +/- 8 mV, P = 0.97), pacing impedance (875 +/- 234 ohms vs 943 +/- 331 ohms, P = 0.24), and stimulation energy threshold (2 +/- 3.2 muJ vs 1.13 +/- 1.5 muJ, P = 0.08). At a median follow-up of 33 months, a significant decrease in stimulation impedance and increase in stimulation energy threshold was observed with unipolar (689 +/- 122 vs 875 +/- 234 ohms, P < 0.01, and 8.34 +/- 10.4 muJ vs 2 +/- 3.2 muJ, P < 0.001, respectively) as well as with bipolar (735 +/- 268 ohms vs 943 +/- 331 ohms, P < 0.01, and 4.81 +/- 9.92 vs 1.13 +/- 1.5 muJ, P = 0.02, respectively) leads. No significant difference in sensing performance was observed with either type of lead (10 +/- 5 mV vs 14 +/- 6 mV and 10 +/- 6 mV vs 14 +/- 8 mV, respectively). At long-term follow-up, no significant difference among any sensing or stimulation parameter was observed between unipolar and bipolar leads. CONCLUSIONS: At long-term follow-up, a significant increase in the energy required for stimulation was observed, whereas sensing performance remained unchanged. The increase in energy capture threshold was less marked with bipolar than with unipolar leads.