Predictive factors and clinical effect of optimized cardiac resynchronization therapy

Emergent role of dynamic optimization in cardiac resynchronization therapy: Systematic review and network meta-analysis

AIMS

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.

Association of QRS narrowing with response to cardiac resynchronization therapy-a systematic review and meta-analysis of observational studies

Prolonged QRS duration, which reflects a higher degree of mechanical dysynchrony, is a predictor of response to CRT. However, the association of QRS narrowing after biventricular pacing with CRT response rates is not clear. Our aim was to conduct a systematic review and meta-analysis on the association between QRS narrowing after cardiac resynchronization therapy (CRT) and clinical and echocardiographic response to CRT in patients with heart failure. Two independent investigators searched MedLine and EMBASE databases through July 2018 without any limitations. Studies providing estimates (continuous data) on the association of QRS shortening with either clinical (defined as New York Heart Association (NYHA) reduction ≥ 1) or echocardiographic (defined as left ventricular end-systolic volume (LVESV) reduction ≥ 15%) response to CRT were finally included in the quantitative synthesis. We included 32 studies (14 studies (1274 patients mean age 64 years old, males 79.3%) using clinical CRT response and 18 studies (1270 patients, mean age 64 years old, males 69.1%) using echocardiographic CRT response). A significant association between QRS narrowing and shorter attained QRS duration with clinical and echocardiographic CRT response was observed. The observed association was independent of the timing of QRS width measurement after CRT implantation. Acute and late improvement of electrical dysynchrony as depicted by QRS narrowing following biventricular pacing is associated with clinical and echocardiographic response to CRT. However, large prospective studies are needed to further examine our findings.

Values of hemodynamic variation in response to passive leg raising in predicting exercise capacity of heart failure with preserved ejection fraction

In heart failure patients with preserved ejection fraction, their hemodynamic parameters usually change when they are from recumbent to passive leg raising. The authors designed this study to investigate the relationship between hemodynamic parameters measured by impedance cardiography (ICG) and 6-minute walk distance (6MWD) of heart failure with preserved ejection fraction (HFPEF). We recruited 49 subjects with HFPEF in the study, and all the subjects were separated into 2 groups: the patients whose hemodynamic parameters rose after passive leg raising were in group 1 (n = 26) and the patients whose hemodynamic parameters did not rise after passive leg raising were in group 2 (n = 23). Our study then compared the 6MWD, left ventricular ejection fraction, and plasma NT-pro-brain natriuretic peptide between the 2 groups. Group 1 had significantly longer 6MWD than group 2 (515.38 ± 24.97 vs 306.39 ± 20.20 m; P = 0.043). Hemodynamic parameters measured by ICG significantly correlated with 6MWD in both groups. Patients whose hemodynamic parameters rose in response to passive leg raising were more likely to have better exercise capacity. Hemodynamic variation in response to passive leg raising measured by ICG may be more sensitive in predicting exercise capacity of patients with HFPEF.

Meta-analysis of effects of optimization of cardiac resynchronization therapy on left ventricular function, exercise capacity, and quality of life in patients with heart failure

The contribution of postimplant optimization of device settings to the beneficial effect of cardiac resynchronization therapy (CRT) in heart failure is uncertain. We performed a meta-analysis to investigate the impact of CRT optimization on the improvement of left ventricular function, exercise capacity, and quality of life. We undertook a systemic review of the evidence from a search of relevant controlled clinical studies in the MEDLINE and EMBASE databases. Changes in left ventricular ejection fraction (LVEF), 6-minute walk distance, and Minnesota Living with Heart Failure score at follow-up were assessed; the primary outcome was ejection fraction. A random-effects model was used to combine weighted mean difference (WMD) and 95% confidence intervals (CIs). A metaregression was undertaken to assess the impact of potential covariates. Data were collated from 13 studies enrolling 1,431 patients (919 optimized and 669 controls). Pooled analysis demonstrated that the optimization procedure resulted in a significant increase in LVEF (WMD 2.6%, 95% CI 0.8 to 4.4, p = 0.001) as compared with a nonoptimized CRT. No improvements with the optimization of CRT were seen in 6-minute walk distance and quality of life (WMD 12 m, 95% CI 23 to 48, p = 0.49, and 3.6, 95% CI 2.2 to 9.5, p = 0.22, respectively); however, this part of the analysis was performed using limited data. Thus, these collated data suggest that the optimization of CRT leads to a significant but small improvement in LVEF in patients with heart failure. Additional, adequately powered studies are needed to evaluate the effects of this procedure on exercise tolerance and quality of life.