The degree of permanent pacemaker dependence and clinical outcomes following transcatheter aortic valve implantation: implications for procedural technique.

Aims: Conduction abnormalities necessitating permanent pacemaker (PPM) implantation remain the most frequent complication post-transcatheter aortic valve implantation (TAVI), yet reliance on PPM function varies. We evaluated the association of right-ventricular (RV)-stimulation rate post-TAVI with 1-year major adverse cardiovascular events (MACE) (all-cause mortality and heart failure hospitalization). Methods and results: This retrospective cohort study of patients undergoing TAVI in two high-volume centers included patients with existing PPM pre-TAVI or new PPM post-TAVI. There was a bimodal distribution of RV-stimulation rates stratifying patients into two groups of either low [≤10%: 1.0 (0.0, 3.6)] or high [>10%: 96.0 (54.0, 99.9)] RV-stimulation rate post-TAVI. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated comparing MACE in patients with high vs. low RV-stimulation rates post-TAVI. Of 4659 patients, 408 patients (8.6%) had an existing PPM pre-TAVI and 361 patients (7.7%) underwent PPM implantation post-TAVI. Mean age was 82.3 ± 8.1 years, 39% were women. A high RV-stimulation rate (>10%) development post-TAVI is associated with a two-fold increased risk for MACE [1.97 (1.20, 3.25), P = 0.008]. Valve implantation depth was an independent predictor of high RV-stimulation rate [odds ratio (95% CI): 1.58 (1.21, 2.06), P=<0.001] and itself associated with MACE [1.27 (1.00, 1.59), P = 0.047]. Conclusion: Greater RV-stimulation rates post-TAVI correlate with increased 1-year MACE in patients with new PPM post-TAVI or in those with existing PPM but low RV-stimulation rates pre-TAVI. A shallower valve implantation depth reduces the risk of greater RV-stimulation rates post-TAVI, correlating with improved patient outcomes. These data highlight the importance of a meticulous implant technique even in TAVI recipients with pre-existing PPMs.

Dose-Dependent Effects of Ranolazine on Reentrant Ventricular Arrhythmias Induced After Subacute Myocardial Infarction in Rabbits.

Ranolazine has been found to prevent ventricular arrhythmias (VAs) during acute myocardial infarction (AMI). This study aimed to investigate its efficacy on VAs induced several days post-MI. For this purpose, 13 anesthetized rabbits underwent coronary artery ligation. Ten of these animals that survived AMI were reanesthetized 3 to 7 days later for electrophysiologic testing. An endocardial monophasic action potential combination catheter was placed in the right ventricle for simultaneous pacing and recording. Monophasic action potential duration, ventricular effective refractory period (VERP), and VAs induced by programmed stimulation were assessed. Measurements were performed during control pacing, and following an intravenous infusion of either a low-dose ranolazine (2.4 mg/kg, R1) or a higher dose ranolazine (4.8 mg/kg cumulative dose, R2). During control stimulation, 2 animals developed primary ventricular fibrillation (VF), 6 sustained ventricular tachycardia (sVT), and 2 nonsustained VT (nsVT). R1 did not prevent the appearance of VAs in any of the experiments; in contrast, it aggravated nsVT into sVT and complicated sVT termination in 2 of 6 animals. Sustained ventricular tachycardia cycle length and VERP were only slightly decreased after R1 (112 ± 5 vs 110 ± 6 ms and 101 ± 11 vs 98 ± 10 ms, respectively). R2 suppressed inducibility of control nsVT, VF, and sVT in 2 animals. In 4 animals with still inducible sVT, R2 significantly prolonged VT cycle length by 150 ± 23 ms (P < .01), and VERP by 120 ± 7 ms (P < .001) versus control. In conclusion, R2 exerted antiarrhythmic efficacy against subacute-MI VAs, whereas R1 rather aggravated than prevented these arrhythmias. Ventricular effective refractory period prolongation could partially explain the antiarrhythmic action of R2 in this rabbit model.

The influence of right ventricular stimulation on acute response to cardiac resynchronisation therapy.

BACKGROUND: The contribution of right ventricular (RV) stimulation to cardiac resynchronisation therapy (CRT) remains controversial. RV stimulation might be associated with adverse haemodynamic effects, dependent on intrinsic right bundle branch conduction, presence of scar, RV function and other factors which may partly explain non-response to CRT. This study investigates to what degree RV stimulation modulates response to biventricular (BiV) stimulation in CRT candidates and which baseline factors, assessed by cardiac magnetic resonance imaging, determine this modulation. METHODS AND RESULTS: Forty-one patients (24 (59 %) males, 67 ± 10 years, QRS 153 ± 22 ms, 21 (51 %) ischaemic cardiomyopathy, left ventricular (LV) ejection fraction 25 ± 7 %), who successfully underwent temporary stimulation with pacing leads in the RV apex (RVapex) and left ventricular posterolateral (PL) wall were included. Stroke work, assessed by a conductance catheter, was used to assess acute haemodynamic response during baseline conditions and RVapex, PL (LV) and PL+RVapex (BiV) stimulation. Compared with baseline, stroke work improved similarly during LV and BiV stimulation (∆+ 51 ± 42 % and ∆+ 48 ± 47 %, both p < 0.001), but individual response showed substantial differences between LV and BiV stimulation. Multivariate analysis revealed that RV ejection fraction (ß = 1.01, p = 0.02) was an independent predictor for stroke work response during LV stimulation, but not for BiV stimulation. Other parameters, including atrioventricular delay and scar presence and localisation, did not predict stroke work response in CRT. CONCLUSION: The haemodynamic effect of addition of RVapex stimulation to LV stimulation differs widely among patients receiving CRT. Poor RV function is associated with poor response to LV but not BiV stimulation.