Left Univentricular Pacing by Rate-Adaptive Atrioventricular Delay in Treatment of Chronic Heart Failure

Rate adaptive pacing in people with chronic heart failure increases peak heart rate but not peak exercise capacity: a systematic review

Rate adaptive cardiac pacing (RAP) allows increased heart rate (HR) in response to metabolic demand in people with implantable electronic cardiac devices (IECD). The aim of this work was to conduct a systematic review to determine if RAP increases peak exercise capacity (peak VO₂) in line with peak HR in people with chronic heart failure. We conducted a systematic literature search from 1980, when IECD and RAP were first introduced, until 31 July 2021. Databases searched include PubMed, Medline, EMBASE, EBSCO, and the Clinical Trials Register. A comprehensive search of the literature produced a total of 246 possible studies; of these, 14 studies were included. Studies and subsequent analyses were segregated according to comparison, specifically standard RAP (RAPON) vs fixed rate pacing (RAPOFF), and tailored RAP (TLD RAPON) vs standard RAP (RAPON). Pooled analyses were conducted for peak VO₂ and peak HR for RAPON vs RAPOFF. Peak HR significantly increased by 15 bpm with RAPON compared to RAPOFF (95%CI, 7.98-21.97, P < 0.0001). There was no significant difference between pacing mode for peak VO₂ 0.45 ml kg^-1 min^-1 (95%CI, - 0.55-1.47, P = 0.38). This systematic review revealed RAP increased peak HR in people with CHF; however, there was no concomitant improvement in peak VO₂. Rather RAP may provide benefits at submaximal intensities by controlling the rise in HR to optimise cardiac output at lower workloads. HR may be an important outcome of CHF management, reflecting myocardial efficiency.

Three-dimensional electroanatomical mapping guidelines for the selection of pacing site to achieve cardiac resynchronization therapy

Objectives

We aimed to evaluate the feasibility of left ventricular electroanatomical mapping to choose between left bundle branch area pacing (LBBAP) or coronary venous pacing (CVP).

Background

There are several ways to achieve left ventricular activation in cardiac resynchronization therapy (CRT): LBBAP and CVP are two possible methods of delivering CRT. However, the criteria for choosing the best approach remains unknown.

Methods

A total of 71 patients with heart failure, reduced ejection fraction, and left bundle branch block (LBBB) were recruited, of which 38 patients underwent the three-dimensional electroanatomical mapping of the left ventricle to accurately assess whether the left bundle branch was blocked and the block level, while the remaining 33 patients were not mapped. Patients with true LBBB achieved CRT by LBBAP, while patients with pseudo-LBBB achieved CRT by CVP. After a mean follow-up of 6 months and 1 year, the QRS duration and transthoracic echocardiography, including mechanical synchrony indices, were evaluated.

Results

Twenty-five patients with true LBBB received LBBAP, while 13 without true LBBB received CVP. Seventeen patients received LBBAP, and 16 patients received CVP without mapping. Paced QRS duration after the implantation of LBBAP and CVP was significantly narrower in the mapping subgroup compared to the non-mapping subgroup. A significant increase in post-implantation left ventricular ejection fraction was observed in patients with LBBAP or CVP, and the mapping subgroup were better than the non-mapping subgroup. After a 12-month follow-up, atrioventricular, intraventricular, and biventricular synchronization were significantly improved in the mapping subgroup compared to non-mapping groups in both LBBAP and CVP.

Conclusion

In our study, three-dimensional electroanatomical mapping was used to choose LBBAP or CVP for heart failure patients, which proved feasible, with better cardiac resynchronization in the long-term follow-up. Therefore, three-dimensional electroanatomical mapping before CRT appears to be a reliable method for heart failure patients with LBBB who are indicated for CRT.

Fusion Pacing with Biventricular, Left Ventricular-only and Multipoint Pacing in Cardiac Resynchronisation Therapy: Latest Evidence and Strategies for Use

Despite advances in the field of cardiac resynchronisation therapy (CRT), response rates and durability of therapy remain relatively static. Optimising device timing intervals may be the most common modifiable factor influencing CRT efficacy after implantation. This review addresses the concept of fusion pacing as a method for improving patient outcomes with CRT. Fusion pacing describes the delivery of CRT pacing with a programming strategy to preserve intrinsic atrioventricular (AV) conduction and ventricular activation via the right bundle branch. Several methods have been assessed to achieve fusion pacing. QRS complex duration (QRSd) shortening with CRT is associated with improved clinical response. Dynamic algorithm-based optimisation targeting narrowest QRSd in patients with intact AV conduction has shown promise in people with heart failure with left bundle branch block. Individualised dynamic programming achieving fusion may achieve the greatest magnitude of electrical synchrony, measured by QRSd narrowing.

Fragmented QRS (fQRS) Complex Predicts Adverse Cardiac Events of ST-Segment Elevation Myocardial Infarction Patients Undergoing Percutaneous Coronary Intervention and Thrombolysis

BACKGROUND ST-segment elevation myocardial infarction (STEMI) is an acute and life-threatening disease. Adverse cardiac events (ACEs) are defined as cardiovascular death or worsening congestive heart failure in STEMI patients. The present study investigated the predictive role of fragmented QRS complex (fQRS) in risks of ACEs in STEMI. MATERIAL AND METHODS This study was a retrospective analysis involving patients who underwent percutaneous coronary intervention (PCI) or thrombolysis. STEMI patients were divided into the fQRS group (259 cases) and the non-fQRS group (161 cases). Basic information and clinical parameters were evaluated. ACEs, including hemodynamic instability, electrical instability (ventricular tachycardia event, ventricular fibrillation or atrioventricular heart-block) and death, were observed. The 12-lead ECG was used to obtain fQRS recordings. Thrombolytic recanalization was evaluated to confirm clinical outcomes of PCI and thrombolysis therapy. RESULTS Hemodynamic instability rates, electrical instability rates, and death in the fQRS group were significantly higher compared to the non-fQRS group (P=0.002, 0.000, and 0.010, respectively). PCI triggered significantly fewer ACEs compared to thrombolytic therapy in the fQRS group (P=0.000, 0.000, and 0.019, respectively). The fQRS group had higher thrombolysis failure rates and three-vessel lesion of coronary artery rates compared to the non-fQRS group (P=0.009 and 0.029, respectively). There were no differences between fQRS and non-fQRS groups in death rates of STEMI patients undergoing PCI and thrombolytic therapy. GRACE scores more than 140, EF less than 35%, and fQRS illustrated predictive potential for ACEs of STEMI patients. CONCLUSIONS fQRS is an independent predictor for the adverse cardiac events of STEMI patients undergoing PCI or thrombolysis.