Cardiac resynchronization therapy with intraoperative epicardial mapping via minithoracotomy: 10 years' experience

The Suboptimal QLV Ratio May Indicate the Need for a Left Bundle Branch Area Pacing-Optimized Cardiac Resynchronization Therapy Upgrade

Background: The QLV ratio (QLV/baseline QRS width) is an established intraoperative-measurable parameter during cardiac resynchronization therapy (CRT) device implantation, potentially predicting the efficacy of electrical resynchronization. Methods: Left bundle branch area pacing-optimized CRT (LOT-CRT) is a novel approach with the potential to improve both responder rate and responder level in the CRT candidate patient group, even when an optimal electro-anatomical left ventricular lead position is not achievable. In our observational study, 72 CRT-defibrillator candidate patients with a QRS duration of 160 ± 12 ms were consecutively implanted. Using a QLV-ratio-based implant strategy, 40 patients received a biventricular CRT device (Biv-CRT) with an optimal QLV ratio (≥70%). Twenty-eight patients with a suboptimal QLV ratio (<70%) were upgraded intraoperatively to a LOT-CRT system. Patients were followed for 12 months. Results: The postoperative results showed a significantly greater reduction in QRS width in the LOT-CRT patient group compared to the Biv-CRT patients (40.4 ± 14 ms vs. 32 ± 13 ms; p = 0.024). At 12 months, the LOT-CRT group also demonstrated a significantly greater improvement in left ventricular ejection fraction (14.9 ± 8% vs. 10.3 ± 7.4%; p = 0.001), and New York Heart Association functional class (1.2 ± 0.5 vs. 0.8 ± 0.4; p = 0.031), and a significant decrease in NT-pro-BNP levels (1863± 380 pg/mL vs. 1238 ± 412 pg/mL; p = 0.012). Notably, the LOT-CRT patients showed results comparable to Biv-CRT patients with a super-optimal QLV ratio (>80%) in terms of QRS width reduction and LVEF improvement. Conclusions: Our single-center study demonstrated the feasibility of a QLV-ratio-based implantation strategy during CRT implantation. Patients with a LOT-CRT system showed significant improvements, whereas Biv-CRT patients with a super-optimal QLV ratio may not be expected to benefit from an additional LOT-CRT upgrade.

Cardiac resynchronization therapy with intraoperative epicardial mapping via minithoracotomy: 10 years' experience

BACKGROUND

Cardiac resynchronization therapy (CRT) is considered an efficient method to improve the left ventricular (LV) dysfunction with left bundle branch block. However, coronary venous anatomy is not appropriate in about 10% of the cases; thus other alternatives, such as epicardial lead implantation via minithoracotomy are needed.

METHODS

During the period 2007-2017, a total of 57 patients were operated at our institute via left anterior minithoracotomy after an unsuccessful transvenous CRT. The best position of the LV epicardial electrode was determined by intraoperative epicardial mapping, that is locating the latest activation spot relative to the right ventricular (RV) electrode. The authors analyzed the survival by Kaplan-Meier estimator with Tarone-Ware equality test and multiple Cox regression analysis, the changes of the LV ejection fraction (LVEF) and dimensions, the development of the impedance and threshold of the LV epicardial electrode, the possible associations between the survival and intraoperative sensed RV-LV activation delay.

RESULTS

The intraoperative RV-LV activation delay was 92.250 ± 26.538 milliseconds. There were no intraoperative complications except ventricular fibrillation in three patients. Within 30 days there were neither wound healing complications nor pocket hematoma. There was no significant difference in survival with regard to gender or etiology, but significantly better survival was found in the cohort with intraoperative sensed RV-LV activation delay >86 milliseconds. The LVEF and dimensions improved following the operation and continued to be improved in the survivors.

CONCLUSION

CRT via minithoracotomy with epicardial mapping is a safe, efficient, simple, and reproducible second-line alternative to the transvenous method.