Cardiac resynchronization therapy defibrillators in patients with permanent atrial fibrillation

Acute echocardiographic and electrocardiographic effects of triggered left ventricular pacing

Cardiac resynchronization therapy (CRT) is an essential pillar in the therapy of heart failure patients with reduced ejection fraction (HFrEF) presenting with broad left bundle branch block (LBBB) or pacemaker dependency. To achieve beneficial effects, CRT requires high bi-ventricular (BiV) pacing rates. Therefore, device-manufacturers designed pacing algorithms which maintain high BiV pacing rates by a left ventricular (LV) pacing stimulus immediately following a right ventricular sensed beat. However, data on clinical impact of these algorithms are sparse. We studied 17 patients implanted with a CRT device providing triggered left ventricular pacing (tLVp) in case of atrioventricular nodal conduction. Assessment of LV dyssynchrony was performed using echocardiographic and electrocardiographic examination while CRT-devices were set to three different settings: 1. Optimized bi-ventricular-stimulation (BiV); 2. Physiological AV nodal conduction (tLVp-off); 3. Physiological AV nodal conduction and tLVp-algorithm turned on (tLVp-on). QRS duration increased when the CRT-device was set to tLVp-off compared to BiV-Stim, while QRS duration was comparable to BiV-Stim with the tLVp-on setting. Echocardiographic analysis revealed higher dyssynchrony during tLVp-off compared to BiV-Stim. TLVp-on did not improve LV dyssynchrony compared to tLVp-off. QRS duration significantly decreased using tLVp-algorithms compared to physiological AV nodal conduction. However, echocardiographic examination could not show functional benefit from tLVp-algorithms, suggesting that these algorithms are inferior to regular biventricular pacing regarding cardiac resynchronization. Therefore, medical treatment and ablation procedures should be preferred, when biventricular pacing rates have to be increased. TLVp-algorithms can be used in addition to these treatment options.

Clinical impacts of sacubitril/valsartan on patients eligible for cardiac resynchronization therapy

AIMS

Sacubitril/valsartan (SAC/VAL) has been used in patients with heart failure and reduced ejection fraction (HFrEF), and cardiac resynchronization therapy (CRT) could benefit the HFrEF patients with wide QRS durations. This study aimed to evaluate the clinical impacts of SAC/VAL on reverse cardiac remodelling in CRT-eligible and CRT-ineligible HFrEF patients with different QRS durations.

METHODS AND RESULTS

The TAROT-HF study was a multicentre, observational study enrolling patients who initiated SAC/VAL from 10 hospitals since 2017. Patients with baseline left ventricular ejection fraction (LVEF) ≤ 35% were classified into two groups: (i) Group 1: CRT-eligible group, patients with left bundle branch block (LBBB) morphology plus QRS duration ≥130 ms or non-LBBB morphology plus QRS duration ≥150 ms; and (ii) Group 2: CRT-ineligible group. Propensity score matching was performed to adjust for confounders, and 1168 patients were analysed. Baseline characteristics were comparable between the two groups. The improvements in LVEF and left ventricular end-systolic volume index (LVESVi) were more significant in Group 2 than in Group 1 after 1 year SAC/VAL treatment (LVEF: 8.4% ± 11.3% vs. 4.5% ± 8.1%, P < 0.001; change percentages in LVESVi: -14.4% ± 25.9% vs. -9.6% ± 23.1%, P = 0.004). LVEF improving to ≥50% in Groups 1 and 2 constituted 5.2% and 20.2% after 1 year SAC/VAL treatment (P < 0.001). Multivariate analyses showed that wide QRS durations were negatively associated with the reverse cardiac remodelling in these HFrEF patients with SAC/VAL treatment.

CONCLUSION

Despite SAC/VAL treatment, wide QRS durations are associated with lower degrees of left ventricular improvement than narrow ones in the HFrEF patients. Optimal intervention timing for the CRT-eligible patients requires further investigation.