The efficacy of left bundle branch pacing (LBBP) as cardiac resynchronization therapy (CRT) has been reported, but LBBP may not always improve conduction disturbance in the left ventricle (LV). To evaluate LV electrical conduction delay during LBBP, we measured conduction time from the pacing at left bundle branch to LV lead sensing (LBBP-LV) in two patients in whom left bundle branch-optimized cardiac resynchronization therapy (LOT-CRT) was attempted. Case 1 was a 77-year-old female with dilated cardiomyopathy (DCM) and left bundle branch block. The QRS duration during LBBP was 160 ms and the interval between the stimulus artifact and peak of the R wave in lead V6 (Stim-V6RWPT) was 74 ms. LBBP-LV at the LV mid-lateral wall and LV mid-posterolateral wall were 112 ms and 102 ms, respectively. Case 2 was a 75-year-old female with DCM and nonspecific intraventricular conduction delay. The QRS duration during LBBP was 156 ms and Stim-V6RWPT was 66 ms. LBBP-LV at the LV mid-anterolateral wall, LV mid-lateral wall, and LV mid-posterolateral wall were 96 ms, 107 ms, and 121 ms, respectively. In conclusion, LBBP-LV at the LV mid-lateral area was relatively long. If LBBP does not improve LV conduction disturbances, LOT-CRT may be more effective.
UNASSIGNED: The efficacy of left bundle branch pacing (LBBP) for cardiac resynchronization therapy (CRT) has been reported. However, if the conduction time from pacing to the left ventricular (LV) lateral area during LBBP is long, LBBP may not improve LV conduction disturbance, resulting in ineffective CRT. In such cases, more effective CRT would be expected with LV lead implantation at the area of the LV conduction delay during LBBP.

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UNASSIGNED: Cardiovascular and noncardiovascular comorbidities have been recognized as predictors of clinical response in patients receiving cardiac resynchronization therapy (CRT). However, data on vitamin D as a predictor of CRT response are conflicting.
UNASSIGNED: We identified studies from MEDLINE and Embase databases, searching from inception to May 2024, to investigate the association between 25-OH vitamin D levels before CRT implantation and outcomes. Studies had to report 25-OH vitamin D levels or the proportion of patients with vitamin D insufficiency and categorize outcomes as CRT responders or nonresponders. We extracted mean 25-OH vitamin D and standard deviations for both groups from each study and calculated the pooled mean difference (MD). We also retrieved risk ratios, and 95% confidence intervals (CIs) for the association between vitamin D insufficiency and lack of CRT response, combining them using the generic inverse variance method.
UNASSIGNED: Our meta-analysis included four studies. CRT responders had higher levels of 25-OH vitamin D than nonresponders, with a pooled MD of 8.04 ng/mL (95% CI: 3.16-12.93; I 2 = 48%, p < .001). Patients with vitamin D insufficiency before implantation had higher odds of lacking response to CRT, with a pooled RR of 3.28 (95% CI: 1.43-7.50; I 2 = 0%, p = .005) compared to those with normal vitamin D.
UNASSIGNED: CRT responders had higher 25-OH vitamin D levels compared to nonresponders. Vitamin D insufficiency was associated with a higher risk of nonresponse to CRT. These findings highlight the importance of monitoring and managing vitamin D levels in these patients.

The impact of age (≥ 85 vs < 85 years) on clinical outcomes and pacemaker performance of conduction system pacing (CSP) compared to right ventricular pacing (RVP) were examined. Consecutive patients from a prospective, observational, multicenter study with pacemakers implanted for bradycardia were studied. The primary endpoint was a composite of heart failure (HF)-hospitalizations, pacing-induced cardiomyopathy requiring cardiac resynchronization therapy or all-cause mortality. Secondary endpoints were acutely successful CSP, absence of pacing-complications, optimal pacemaker performance defined as pacing thresholds < 2.5 V, R-wave amplitude ≥ 5 V and absence of complications, threshold stability (no increases of > 1 V) and persistence of His-Purkinje capture on follow-up. Among 984 patients (age 74.1 ± 11.2 years, 41% CSP, 16% ≥ 85 years), CSP was independently associated with reduced hazard of the primary endpoint compared to RVP, regardless of age-group (< 85 years: adjusted hazard ratio [AHR] 0.63, 95% confidence interval [CI] 0.40-0.98; ≥ 85 years: AHR 0.40, 95% CI 0.17-0.94). Among patients with CSP, age did not significantly impact the secondary endpoints of acute CSP success (86% vs 88%), pacing complications (19% vs 11%), optimal pacemaker performance (64% vs 69%), threshold stability (96% vs 96%) and persistent His-Purkinje capture (86% vs 91%) on follow-up (all p > 0.05). CSP improves clinical outcomes in all age-groups, without compromising procedural safety or pacemaker performance in the very elderly.

Multiple methods are used to tackle ipsilateral obstructed venous access in patients undergoing a device upgrade by implanting a new left ventricular lead. One feasible solution to tackle this is implantation of the upgrade lead contralaterally with pre-sternal tunnelization to the opposite side under conscious sedation.

Objective: The feasibility of the conduction system pacing (CSP) upgrade as an alternative modality to the traditional biventricular pacing (BiVP) upgrade in patients with pacemaker-induced cardiomyopathy (PICM) remains uncertain. This study sought to compare two modalities of CSP (His bundle pacing (HBP) and left bundle branch pacing (LBBP)) with BiVP and no upgrades in patients with pacing-induced cardiomyopathy. Methods: This retrospective analysis comprised consecutive patients who underwent either BiVP or CSP upgrade for PICM at the cardiac department from 2017 to 2021. Patients with a follow-up period exceeding 12 months were considered for the final analysis. Results: The final group of patients who underwent upgrades included 48 individuals: 11 with BiVP upgrades, 24 with HBP upgrades, and 13 with LBBP upgrades. Compared to the baseline data, there were significant improvements in cardiac performance at the last follow-up. After the upgrade, the QRS duration (127.81 ± 31.89 vs 177.08 ± 34.35 ms, p < 0.001), NYHA class (2.28 ± 0.70 vs 3.04 ± 0.54, p < 0.05), left ventricular end-diastolic diameter (LVEDD) (54.08 ± 4.80 vs 57.50 ± 4.85 mm, p < 0.05), and left ventricular ejection fraction (LVEF) (44.46% ± 6.39% vs 33.15% ± 5.25%, p < 0.001) were improved. There was a noticeable improvement in LVEF in the CSP group (32.15% ± 3.22% vs 44.95% ± 3.99% (p < 0.001)) and the BiVP group (33.90% ± 3.09% vs 40.83% ± 2.99% (p < 0.001)). The changes in QRS duration were more evident in CSP than in BiVP (56.65 ± 11.71 vs 34.67 ± 13.32, p < 0.001). Similarly, the changes in LVEF (12.8 ± 3.66 vs 6.93 ± 3.04, p < 0.001) and LVEDD (5.80 ± 1.71 vs 3.16 ± 1.35, p < 0.001) were greater in CSP than in BiVP. The changes in LVEDD (p = 0.549) and LVEF (p = 0.570) were similar in the LBBP and HBP groups. The threshold in LBBP was also lower than that in HBP (1.01 ± 0.43 vs 1.33 ± 0.32 V, p = 0.019). Conclusion: The improvement of clinical outcomes in CSP was more significant than in BiVP. CSP may be an alternative therapy to CRT for patients with PICM. LBBP would be a better choice than HBP due to its lower thresholds.

OBJECTIVE: Suboptimal device programming is frequent in non-responders to cardiac resynchronization therapy (CRT). However, the role of device optimization and the most appropriate technique are still unknown. The aim of our study was to analyse the effect of different CRT optimization techniques within a network meta-analysis.
METHODS: A systematic search was conducted on MEDLINE, Embase and CENTRAL for studies comparing outcomes with empirical device settings or optimization using echocardiography, static algorithms or dynamic algorithms. Studies investigating the effect of optimization in non-responders were also analysed.
RESULTS: A total of 17 studies with 4346 patients were included in the quantitative analysis. Of the treatments and outcomes examined, a significant difference was found only between dynamic algorithms and echocardiography, with the former leading to a higher echocardiographic response rate [odds ratio (OR): 2.02, 95% confidence interval (CI) 1.21-3.35], lower heart failure hospitalization rate (OR: 0.75, 95% CI 0.57-0.99) and greater improvement in 6-minute walk test [mean difference (MD): 45.52 m, 95% credible interval (CrI) 3.91-82.44 m]. We found no significant difference between empirical settings, static algorithms and dynamic algorithms. Seven studies with 228 patients reported response rates after optimization in non-responders. Altogether, 34.3%-66.7% of initial non-responders showed improvement after optimization, depending on response criteria.
CONCLUSIONS: At the time of CRT implantation, dynamic algorithms may serve as a resource-friendly alternative to echocardiographic optimization, with similar or better mid-term outcomes. However, their superiority over empirical device settings needs to be investigated in further trials. For non-responders, CRT optimization should be considered, as the majority of patients experience improvement.

OBJECTIVE: To evaluate the efficacy of cardiac resynchronization therapy (CRT) in patients with chronic heart failure (CHF) associated with cardiac dyssynchrony and to identify the factors that influence the CRT efficacy.
METHODS: This retrospective study included 155 patients after implantation of CRT devices. The CRT devices with a built-in cardioverter-defibrillator (CRT-D) and without it (CRT-P) were implanted in 139 (89.7%) and 16 (10.3%) patients, respectively. The follow-up period was 52.37±35.94 months. Based on the study results, two groups of patients were formed depending on the presence of a clinical response to CRT, responders and non-responders. The factors that influenced the clinical response to CRT were studied. The effect of the baseline state of patients on the effect of therapy was assessed. The need for CRT optimization and a possibility of using electrocardiographic criteria for that purpose were studied. Modern devices and leads for CRT, their functional capabilities and their influence on the CRT efficacy were characterized. Statistical analysis was performed with an IBM SPSS Statistics 21.0 (Chicago, USA) package.
RESULTS: CRT implantation with the left ventricular lead placement according to the traditional technique, through the coronary sinus, was successful in 130 (87.9%) patients. Difficulties with the left ventricular lead placement were noted in 13 (8.3%) patients when other techniques were used. After 6 months, a hemodynamic and clinical response was observed in 112 (72.2%) patients, and no positive response in 43 (27.8%). The increase in left ventricular ejection fraction in the responder group was more than 21.8±3.7%, which was associated with an improvement of the 6-minute walk test results. Th clinical response was significantly influenced by the possibility of stimulation from the basal parts of the heart; the use of more modern devices for CRT and quadripolar left ventricular leads; timely CRT optimization; and persistent dyssynchrony in non-responders. During the follow-up period, 34 (21.9%) patients died. The death rate in the non-responder group was significantly higher than in the responder group, 18 (41.3%) vs. 16 (14.3%), p=0.001. The main cause of death in the group of non-responders was CHF. Heart transplantation was performed in 3 (1.9%) patients.
CONCLUSIONS: CRT increases the life span and improves the quality of life in patients with CHF and cardiac dyssynchrony. There was a group of patients with no benefit from CRT in this study. Modern devices allow increasing the number of patients who benefit from CRT. Periodic optimization of CRT is necessary. When optimizing CRT, it is possible to use electrocardiographic criteria of effectiveness: duration of the QRS complex and changes in the position of the electrical axis of the heart.

BACKGROUND: The fibrosis-5 (FIB-5) index is a noninvasive marker for assessing the progression of liver fibrosis and predictor in patients with heart failure (HF). This study investigated the association between the FIB-5 index and response to cardiac resynchronization therapy (CRT) and evaluated its predictive value for prognosis.
METHODS: In total, 203 patients who underwent CRT/CRT-defibrillator (CRT-D) implantation were retrospectively included. The FIB-5 index was calculated using blood samples obtained before and after CRT/CRT-D. Response to CRT was defined as a relative reduction in left ventricular end-systolic volume of ≥15% 6 months after CRT/CRT-D. We compared the prognosis after CRT/CRT-D between the groups according to the FIB-5 index.
RESULTS: One hundred and twenty-three patients (61%) responded to CRT. The responder group demonstrated a significantly higher FIB-5 index than the nonresponder group (-2.76 ± 3.85 vs. -4.67 ± 3.29, p < 0.001). Receiver-operating characteristic analysis demonstrated that the area under the curve of the FIB-5 index was 0.660 with a cutoff value of -4.00 for responders. In multivariate analysis, FIB-5 index ≥ -4.00 was an independent predictor for CRT response (odds ratio: 3.665, p = 0.003), in addition to QRS duration ≥ 150 ms and echocardiographic dysynchrony. The FIB-5 index increased significantly after 6 months in the responder group but not in the nonresponder group. The FIB-5 index ≥ -4.00 group showed a significantly better prognosis for cardiac death, HF hospitalization, and composite endpoint than the FIB-5 index < -4.00 group.
CONCLUSIONS: The FIB-5 index in addition to classical predictors may be a useful marker for predicting response to CRT.

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