Aims: To investigate the feasibility of transvenous left ventricular (LV) pacing by autocapture at long term. A reliable measurement of LV evoked response (ER) is the pivotal requirement for beat-to-beat detection of ventricular capture and automatic output adjustment.
Methods and results: Seven patients with accepted class I indication to permanent cardiac pacing received a DDDR pacemaker with automatic output adjustment based on beat-to-beat capture verification (Insignia Ultra 1290, Guidant), whose ventricular port was connected to a LV lead placed in a branch of the coronary sinus. The device allows LV threshold trending, performing a threshold test every 21 h, and diagnoses acute and non-acute issues of ER detection during follow up. Average follow up after implantation was 34 +/- 6 months (range 28-45, median 34). Left ventricular pacing threshold showed an increase from implantation (1.2 +/- 0.4 V at 0.4 ms) that peaked at week 4 (1.6 +/- 0.7 V at 0.4 ms), and returned to baseline (1.1 +/- 0.5 at 0.4 ms) by the end of the 7th week. Autocapture performance at long term, as assessed by the trend of LV threshold and of ER diagnostic issues, did not show any pitfall.
Conclusions: Our observations support the feasibility and safety of capture verification during LV pacing alone. A possible application of this pacing technology could be biventricular stimulation.