Introduction
In cardiac resynchronization therapy, pacing the left ventricle (LV) at sites of prolonged electrical delay is associated with better outcomes. We sought to characterize the interrelationships between intrinsic, right‐ventricular (RV)‐paced, and LV‐paced interventricular delays.
Methods and Results
The following electrical timings were measured at implantation for all electrodes of the LV quadripolar leads: QLV, interventricular delay in intrinsic rhythm (RVs‐LVs), in RV‐paced rhythm (RVp‐LVs), and in LV‐paced rhythm (LVp‐RVs). We included 32 patients (78% men, age 72 years, LV ejection fraction 29%, left bundle branch block 84%). QLV and RVs‐LVs were correlated (R2 = .72, p < .0001), as were RVs‐LVs and RVp‐LVs (R2 = .27, p = .002) and RVp‐LVs and LVp‐RVs (R2 = .60, p < .001). Direction of activation along the four LV lead electrodes was concordant between RVs‐LVs and RVp‐LVs in only 17 (53%) patients. The latest‐activated electrodes in RVs‐LVs and RVp‐LVs were concordant in 26 (81%) patients, adjacent in 3 (9%) patients, and remote in 3 (9%) patients. Biventricular‐paced QRS duration varied by more than 10 ms between the two electrodes in half of the patients with dissimilar latest electrodes. Among the seven echocardiographic nonresponders at 6 months, the programmed electrode was remote from the latest electrode in RVs‐LVs in five patients and in RVp‐LVs in three patients.
Conclusion
Intrinsic and RV‐paced interventricular electrical delays are correlated, but there is substantial heterogeneity between patients. The latest‐activated electrode may be different between RVs‐LVs and RVp‐LVs, and this might have important implications in selecting the optimal LV vector.
Introduction
By stabilizing transthyretin tetramer, tafamidis delays neurological progression in mutated Transthyretin amyloidosis (mATTR) and has replaced liver transplantation (LT) as the first-line therapy in European patients with stage I mATTR. To date, no study compared these two therapeutic strategies.
Material and methods
Stage I mATTR patients treated either with tafamidis or with LT were compared using a propensity score. The primary endpoint was the all-cause mortality. Secondary endpoints were the neurological progression (assessed by a worsening in the PND score) and the cardiac progression of mATTR (defined by a cardiovascular death or the onset or the worsening of symptomatic heart failure).
Results
The files of 345 patients with proven mATTR were analyzed and 144 patients entered the final analysis (72 patients in each group, median age 54 years, 60% carrying the V30M mutation). Patients treated by tafamidis had a better survival than patients with LT (HR: 0.93; 95% CI: 0.17–0.91; P=0.029). Conversely, the worsening-free survival of the neurological status was significantly shorter for patients that received tafamidis than for LT patients (HR: 6.08; 95% CI: 2.97–12.45; P<0.0001). A similar non-significant trend was documented regarding the progression of the cardiac status (HR: 1.99; 95CI: 0.91–4.34; P=0.084).
Conclusions
In mATTR, first-line therapy with tafamidis was associated with a better survival than LT. Conversely, LT provided better neurological stabilization than tafamidis. These results confirm that LT remains a major treatment in mATTR. In patients treated with tafamidis, close follow up of the treatment efficacy is mandatory.
The combination of choosing the best quadripolar pacing configuration and optimizing atrioventricular and interventricular delays resulted in an improvement of cardiac output compared to standard biventricular stimulation in 68% of patients. The final cardiac output was comparable to multipoint pacing.
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