Predictive factors of difficult implantation procedure in cardiac resynchronization therapy.

AIMS: The usefulness of cardiac resynchronization therapy (CRT) in patients with congestive heart failure is offset by its long, user-dependent, and technical procedure. No studies have been published regarding factors related to CRT implantation procedure duration and X-ray exposure. Additionally, only a few studies have investigated the predictive factors of primary left ventricular (LV) lead implant failure. The aim of this prospective study was two-fold: (i) to evaluate the prevalence and predictive factors of prolonged CRT implantation procedure and (ii) to identify the predictive factors of primary LV lead implantation failure.

METHODS AND RESULTS: Between November 2008 and September 2009, 128 consecutive patients underwent CRT implantation; of these, 22 patients (17.2%) were excluded because of CRT generator replacement. Population characteristics were a mean age of 69 +/- 10 years, 28.3% female, New York Heart Association class 3.2 +/- 0.3, LV ejection fraction (LVEF; 29 +/- 6%), and QRS width 146 +/- 23 ms. Cardiac resynchronization therapy implantation was attempted in 106 patients, and first LV lead implantation was obtained in 96 of 106 patients (90.5% primary success). Ten primary implantations failed (9.5%), due to unsuccessful LV lead implants. A second procedure was successfully attempted in six patients with a second more experienced operator (5.7%). Among the remaining four patients, one patient required a surgical epicardial LV lead implantation, and the implantation was not reattempted in the other three patients. The overall success rate of CRT system implantation was 96.2% (102 of 106 patients). Procedure parameters were as follows: LV threshold (1.4 +/- 0.9 V); LV wave amplitude (15 +/- 8 mV); LV impedance (874 +/- 215 ohm); median procedure time (skin to skin), 55 min (45-80); and median of procedure fluoroscopy time, 11 min (6.2-29). In 24 patients (22.6%), difficult procedures requiring >or=85 min of implantation duration occurred. By univariate analysis, predictive factors of difficult implantation were LV ejection fraction (25.6 +/- 6 vs. 30.2 +/- 8%; P = 0.02), LV end-diastolic diameter (72.4 +/- 11 vs. 66 +/- 11 mm; P = 0.01), LV end-systolic diameter (LVESD; 62 +/- 12 vs. 56 +/- 12 mm, P = 0.04), and the operator's experience (very experienced operator vs. less experienced operator, P = 0.006). By multivariate analysis, only primary LV lead implantation failure, LVESD, and operator's experience were independently associated with difficult procedures. In this patient subset with primary LV lead implant failure (n = 10), the only independent predictive factor was the LV end-systolic volume (P = 0.03).

CONCLUSION: In this study, the rate of difficult CRT device implantation procedures approached 25%. Both the degree of LV dysfunction and the operator's experience were independent predictors of surgical difficulties. Left ventricular end-systolic volume was the only independent predictor of primary LV lead implant failure.