Cardiac resynchronisation therapy optimisation of interventricular delay by the systolic dyssynchrony index: A comparative, randomised, 12-month follow-up study

Clinical outcomes of automatic algorithms in cardiac resynchronization therapy: Systematic review and meta-analysis

Background

Algorithms to automatically adjust atrioventricular (AV) and interventricular (VV) intervals in cardiac resynchronization therapy (CRT) devices are common, but their clinical efficacy is unknown.

Objective

The purpose of this study was to evaluate automatic CRT algorithms in patients with heart failure for the reduction of mortality, heart failure hospitalizations, and clinical improvement.

Methods

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) in patients with CRT using automatic algorithms that change AV and VV intervals dynamically without manual input, on a beat-to-beat basis. We performed a subgroup analysis including intracardiac electrogram-based (EGM) algorithms and contractility-based algorithms.

Results

Nine RCTs with 8531 participants were included, of whom 4275 (50.1%) were randomized to automatic algorithm. Seven of the 9 trials used EGM-based algorithms, and 2 used contractility sensors. There was no difference in all-cause mortality (10.3% vs 11.3%; odds ratio [OR] 0.90; 95% confidence interval [CI] 0.71-1.03; P = .13; I2 = 0%) or heart failure hospitalizations (15.0% vs 16.1%; OR 0.924; 95% CI 0.81-1.04; P = .194; I2 = 0%) between the automatic algorithm group and the control group. Study-defined clinical improvement was also not significantly different between groups (66.6% vs 63.3%; risk ratio 1.01; 95% CI 0.95-1.06; P = .82; I2 = 50%). In the contractility-based subgroup, there was a trend toward greater clinical improvement with the use of the automatic algorithm (75% vs 68.3%; OR 1.45; 95% CI 0.97-2.18; P = .07; I2 = 40%), which did not reach statistical significance. The overall risk of bias was low.

Conclusion

Automatic algorithms that change AV or VV intervals did not improve mortality, heart failure hospitalizations, or cardiovascular symptoms in patients with heart failure and CRT.

Cardiac Resynchronization Therapy in Non-Ischemic Cardiomyopathy: Role of Multimodality Imaging

Non-ischemic cardiomyopathy encompasses a heterogeneous group of diseases, with a generally unfavorable long-term prognosis. Cardiac resynchronization therapy (CRT) is a useful therapeutic option for patients with symptomatic heart failure, currently recommended by all available guidelines, with outstanding benefits, especially in non-ischemic dilated cardiomyopathy. Still, in spite of clear indications based on identifying a dyssynchronous pattern on the electrocardiogram (ECG,) a great proportion of patients are non-responders. The idea that multimodality cardiac imaging can play a role in refining the selection criteria and the implant technique and help with subsequent system optimization is promising. In this regard, predictors of CRT response, such as apical rocking and septal flash have been identified. Promising new data come from studies using cardiac magnetic resonance and nuclear imaging for showcasing myocardial dyssynchrony. Still, to date, no single imaging predictor has been included in the guidelines, probably due to lack of validation in large, multicenter cohorts. This review provides an up-to-date synthesis of the latest evidence of CRT use in non-ischemic cardiomyopathy and highlights the potential additional value of multimodality imaging for improving CRT response in this population. By incorporating all these findings into our clinical practice, we can aim toward obtaining a higher proportion of responders and improve the success rate of CRT.

Echocardiography for the management of patients with biventricular pacing: Possible roles in cardiac resynchronization therapy implementation

Cardiac resynchronization therapy (CRT) is an established therapeutic option for the subset of patients with heart failure (HF), reduced ejection fraction (EF), and dyssynchrony evidenced by electrocardiography. Benefit from CRT has been proven in many clinical trials, yet a sizeable proportion of these patients with wide QRS do not respond to this intervention, despite the updated practice guidelines. Several echocardiographic indices, targeting mechanical rather than electrical dyssynchrony, have been suggested to address this issue, but research so far has not succeeded in providing a single and simple measurement with adequate sensitivity and specificity for identification of responders. While there is still ongoing research in this field, echocardiography proves helpful in other aspects of CRT implementation, such as site selection for left ventricular (LV) lead pacing and optimization of pacing parameters during follow-up visits.