His-Purkinje Conduction System Pacing Optimized Trial of Cardiac Resynchronization Therapy vs Biventricular Pacing: HOT-CRT Clinical Trial

BACKGROUND

His-Purkinje conduction system pacing (HPCSP) using His bundle pacing (HBP) or left bundle branch pacing (LBBP) has emerged as an alternative to biventricular pacing (BVP) in patients requiring cardiac resynchronization therapy (CRT).

OBJECTIVES

The aim of the study was to compare the feasibility and clinical efficacy of HOT-CRT (His-Purkinje conduction system pacing Optimized Trial of Cardiac Resynchronization Therapy) with BVP in patients with heart failure, reduced ejection fraction, and indication for CRT.

METHODS

This was a prospective, randomized, controlled trial of HOT-CRT and BVP in patients with LVEF <50% and indications for CRT. If HPCSP resulted in incomplete electrical resynchronization, a coronary sinus (CS) lead was added. The primary outcome was the change in left ventricular ejection fraction (LVEF) at 6 months. The primary safety endpoint was freedom from major complications.

RESULTS

A total of 100 patients (female 31%, aged 70 ± 12 years, LVEF 31.5% ± 9.0%) were randomized. HOT-CRT was successful in 48 of 50 (96%) and BVP-CRT in 41 of 50 (82%) patients (P = 0.03). QRS duration significantly decreased from 164 ± 26 ms to 137 ± 20 ms with HOT-CRT and 166 ± 28 ms to 141 ± 19 ms with BVP. Fluoroscopy results (18.8 ± 12.4 min vs 23.8 ± 12.4 min, P = 0.05) and procedure duration (119 ± 42 min vs 114 ± 36 min, P = 0.5) were similar. The primary outcome of change in LVEF at 6 months was greater in HOT-CRT than in BVP (12.4% ± 7.3% vs 8.0% ± 10.1%, P = 0.02). The primary safety endpoint was similar (98% vs 94%, P = 0.62). Echocardiographic response of improvement in LVEF >5% occurred in 80% vs 61% (P = 0.06). Complications occurred in 3 (6%) in HOT-CRT vs 10 (20%) in BVP (P = 0.03).

CONCLUSIONS

HPCSP-guided CRT resulted in greater change in LVEF compared with BVP. Randomized clinical trials with long-term follow-up are necessary. (His-Purkinje Conduction System Pacing Optimized Trial of Cardiac Resynchronization Therapy [HOT-CRT]; NCT04561778).

Clinical outcomes of conduction system pacing compared to biventricular pacing in patients requiring cardiac resynchronization therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is well-established therapy in patients with reduced left ventricular ejection fraction (LVEF) and bundle branch block or indication for pacing. Conduction system pacing (CSP) using His-bundle pacing (HBP) or left bundle branch area pacing (LBBAP) has been shown to be a safe and more physiological alternative to BVP.

OBJECTIVE

The purpose of this study was to compare the clinical outcomes between CSP and BVP among patients undergoing CRT.

METHODS

This observational study included consecutive patients with LVEF ≤35% and class I or II indications for CRT who underwent successful BVP or CSP at 2 major health care systems. The primary outcome was the composite endpoint of time to death or heart failure hospitalization (HFH). Secondary outcomes included subgroup analysis in left bundle branch block as well as individual endpoints of death and HFH.

RESULTS

A total of 477 patients (32% female) met inclusion criteria (BVP 219; CSP 258 [HBP 87, LBBAP 171]). Mean age was 72 ± 12 years, and mean LVEF was 26% ± 6%. Comorbidities included hypertension 70%, diabetes mellitus 45%, and coronary artery disease 52%. Paced QRS duration in CSP was significantly narrower than BVP (133 ± 21 ms vs 153 ± 24 ms; P <.001). LVEF improved in both groups during mean follow-up of 27 ± 12 months and was greater after CSP compared to BVP (39.7% ± 13% vs 33.1% ± 12%; P <.001). Primary outcome of death or HFH was significantly lower with CSP vs BVP (28.3% vs 38.4%; hazard ratio 1.52; 95% confidence interval 1.082-2.087; P = .013).

CONCLUSION

CSP improved clinical outcomes compared to BVP in this large cohort of patients with indications for CRT.

Conduction System Pacing versus Conventional Pacing in Patients Undergoing Atrioventricular Node Ablation: Non-randomized, On-Treatment Comparison

Background

Atrioventricular node ablation (AVNA) with right ventricular or biventricular pacing (conventional pacing; CP) is an effective therapy for patients with refractory atrial fibrillation (AF). Conduction system pacing (CSP) using His bundle pacing or left bundle branch area pacing preserves ventricular synchrony.

Objective

The aim of our study is to compare the clinical outcomes between CP and CSP in patients undergoing AVNA.

Methods

Patients undergoing AVNA at Geisinger Health System between January 2015 and October 2020 were included in this retrospective observational study. CP or CSP was performed at the operators’ discretion. Procedural, pacing parameters, and echocardiographic data were assessed. Primary outcome was the combined endpoint of time to death or heart failure hospitalization (HFH) and was analyzed using Cox proportional hazards. Secondary outcomes were individual outcomes of time to death and HFH.

Results

AVNA was performed in 223 patients (CSP, 110; CP, 113). Age was 75 ± 10 years, male 52%, hypertension 67%, diabetes 25%, coronary disease 40%, and left ventricular ejection fraction (LVEF) 43% ± 15%. QRS duration increased from 103 ± 30 ms to 124 ± 20 ms (P < .01) in CSP and 119 ± 32 ms to 162 ± 24 ms in CP (P < .001). During a mean follow-up of 27 ± 19 months, LVEF significantly increased from 46.5% ± 14.2% to 51.9% ± 11.2% (P = .02) in CSP and 36.4% ± 16.1% to 39.5% ± 16% (P = .04) in CP. The primary combined endpoint of time to death or HFH was significantly reduced in CSP compared to CP (48% vs 62%; hazard ratio 0.61, 95% confidence interval 0.42–0.89, P < .01). There was no reduction in the individual secondary outcomes of time to death and HFH in the CSP group compared to CP.

Conclusion

CSP is a safe and effective option for pacing in patients with AF undergoing AVNA in high-volume centers.

Clinical outcomes of left bundle branch area pacing compared to right ventricular pacing: Results from the Geisinger-Rush Conduction System Pacing Registry

BACKGROUND

Left bundle branch area pacing (LBBAP) has been shown to be a feasible option for patients requiring ventricular pacing.

OBJECTIVE

The purpose of this study was to compare clinical outcomes between LBBAP and RVP among patients undergoing pacemaker implantation METHODS: This observational registry included patients who underwent pacemaker implantations with LBBAP or RVP for bradycardia indications between April 2018 and October 2020. The primary composite outcome included all-cause mortality, heart failure hospitalization (HFH), or upgrade to biventricular pacing. Secondary outcomes included the composite endpoint among patients with a prespecified burden of ventricular pacing and individual outcomes.

RESULTS

A total of 703 patients met inclusion criteria (321 LBBAP and 382 RVP). QRS duration during LBBAP was similar to baseline (121 ± 23 ms vs 117 ± 30 ms; P = .302) and was narrower compared to RVP (121 ± 23 ms vs 156 ± 27 ms; P <.001). The primary composite outcome was significantly lower with LBBAP (10.0%) compared to RVP (23.3%) (hazard ratio [HR] 0.46; 95%T confidence interval [CI] 0.306-0.695; P <.001). Among patients with ventricular pacing burden >20%, LBBAP was associated with significant reduction in the primary outcome compared to RVP (8.4% vs 26.1%; HR 0.32; 95% CI 0.187-0.540; P <.001). LBBAP was also associated with significant reduction in mortality (7.8% vs 15%; HR 0.59; P = .03) and HFH (3.7% vs 10.5%; HR 0.38; P = .004).

CONCLUSION

LBBAP resulted in improved clinical outcomes compared to RVP. Higher burden of ventricular pacing (>20%) was the primary driver of these outcome differences.

Successful use of wearable cardioverter defibrillator in a patient with dextrocardia and persistent left superior vena cava

Congenital disorders, such as dextrocardia and persistent left superior vena cava, are rare. However, their presence is often associated with other cardiac anomalies, and may lead to lethal ventricular tachyarrhythmias, which result in sudden cardiac death. Treating patients with these disorders can present a challenge to clinicians, as it may cause technical difficulties during interventional procedures, and more often, altered defibrillation techniques in a setting of prehospital sudden cardiac arrest. This report describes the first case of successful defibrillation therapy delivered by the wearable cardioverter defibrillator to a patient with dextrocardia and persistent left superior vena cava during a ventricular tachycardia arrest.

Cardiac Tamponade as Complication of Active-Fixation Atrial Lead Perforations: Proposed Mechanism and Management Algorithm

BACKGROUND

Cardiac tamponade is a rare complication after implantation of dual chamber pacemaker or defibrillator systems. Its pathophysiology and optimal management are not currently well established.

METHODS

Three cases of cardiac tamponade following successful implantation of transvenous dual chamber pacemakers with active-fixation atrial leads were identified.

RESULTS

All three patients with post-implant cardiac tamponade were suspected to have the same etiology of bleeding into the pericardial space. This was due to protrusion of the helix of the active-fixation atrial pacing lead through the atrial wall with subsequent abrasion of visceral pericardial layer and bleeding from the atrium through the perforation. In two patients, the perforation sites were visualized and repaired during open thoracotomy in the operating room. The third patient underwent lead repositioning under fluoroscopic guidance in the electrophysiology laboratory.

CONCLUSION

Based on the reviewed cases, we describe the pathophysiology of, and recommend a safe conservative algorithm for, the management of cardiac tamponade after successful transvenous lead implantation. Percutaneous pericardiocentesis with placement of the pericardial drain followed by lead repositioning under fluoroscopic guidance with surgical backup appears to be safe and effective.

Normothermia is protective during infrarenal aortic surgery

PURPOSE

Mild hypothermia has been suggested to be protective against tissue ischemia during aortic operations. However, recent studies have documented detrimental cardiac effects of hypothermia during a variety of operative procedures. The influence of different warming methods and the impact of hypothermia during standard aortic procedures was assessed.

METHODS

One hundred patients who underwent repair of infrarenal aortic aneurysms or aortoiliac occlusive disease were prospectively randomized into 2 groups, receiving either a circulating water mattress or a forced air warming blanket. Adjuvant warming methods were standardized. The day before surgery, 48-hour Holter monitors were applied and interpreted by a cardiologist blinded to the treatment. Randomization resulted in equivalent groups with regard to patient history, indications for surgery, body mass index, length of surgery, and fluid requirements.

RESULTS

Core temperatures were significantly warmer during surgery (36.3 degrees C +/- 0.7 degrees C vs 35.4 +/- 0.8 degrees C) and after surgery (36.4 degrees C +/- 0.7 degrees C vs 35.6 degrees C +/- 0.9 degrees C) in patients with forced air warming (P <.001). The circulating water mattress group had significantly more metabolic acidosis perioperatively (P =.03). Postoperative length of stay, cardiac complications, and death rates were not significantly different. Subgroup analysis of 83 aneurysm patients comparing normothermia with hypothermia (temperature less than 36 degrees C) on arrival to the recovery room identified decreased cardiac output (P =.02), thrombocytopenia (P =.02), elevated prothrombin time (P =.04), and inferior Acute Physiology and Chronic Health Evaluation (APACHE) II scores (P <.001) in the hypothermic group. Holter analysis revealed more sinus tachycardia (ST) segment changes and ventricular tachycardia in hypothermic aneurysm patients (P =.05).

CONCLUSION

Patients treated with forced air blankets had significantly less metabolic acidosis and were kept significantly warmer than those treated with circulating water mattresses. Patients with aneurysms that were kept normothermic had a significantly improved clinical profile, with fewer cardiac events on the Holter recordings. We therefore conclude that (1) normothermia is protective for infrarenal aortic surgical patients; and (2) forced air warming blankets provide improved temperature maintenance compared with circulating water mattresses.

A functional approach to the preexcitation syndromes

Electrophysiologic studies have been used to elicit the mechanisms of the preexcitation syndromes and have become a therapeutic tool over the past decade. A thorough understanding of the physiology and anatomy of accessory pathways that are responsible for preexcitation and the associated arrhythmias is necessary before considering the various forms of intervention. The approach to patients with preexcitation syndromes is discussed, with an emphasis on the functional properties of accessory pathways and the associated arrhythmias.

Myosin light chain phosphorylation in 32P-labeled rabbit aorta stimulated by phorbol 12,13-dibutyrate and phenylephrine

The mechanism(s) of force development in vascular smooth muscle following pharmacological activation of protein kinase C by phorbol esters are not known. In this study, we examined the myosin light chain phosphorylation response following stimulation by phorbol 12,13-dibutyrate (PDB) or phenylephrine in rabbit aorta which had been incubated with 32PO4 in order to label ATP pools. Through tryptic phosphopeptide mapping of myosin light chain from intact tissue and comparison to controls using purified components, we inferred that Ca2+-dependent force stimulated by PDB was associated with small increases in serine-19 phosphorylation, consistent with a contractile mechanism involving indirect activation of myosin light chain kinase. Additional residues, consistent with the in vitro substrate specificity of protein kinase C, were also observed to be phosphorylated in response to PDB and represented proportionately a larger fraction of the total phosphorylated myosin light chain in Ca2+-depleted tissues. Stimulation by an alpha 1-adrenergic agonist (phenylephrine) resulted in phosphorylation of residues which were consistent with an activation mechanism involving myosin light chain kinase only. These results indicate that in rabbit aorta the contractile effects of PDB may be partially mediated by Ca2+-dependent activation of myosin light chain kinase. However, the data do not rule out a component of the PDB-stimulated contractile response which is independent of myosin light chain phosphorylation on the serine-19 residue. In addition, activation by a more physiological stimulus, phenylephrine, does not result in protein kinase C-mediated myosin light chain phosphorylation.

Chylous ascites after abdominal aortic aneurysmectomy: successful management with a peritoneovenous shunt

Postoperative chylous ascites is a rare complication of aortic aneurysmectomy. Although increasing numbers of abdominal aortic aneurysms are being resected annually, there have been only eight previously reported cases of chylous ascites after this operation. This article describes the ninth case of postoperative chylous ascites after abdominal aortic aneurysm resection and emphasizes the value of management with peritoneovenous shunting.

The preoperative liver scan and surgical decision-making in patients with colorectal cancer

The influence of preoperative liver scans and liver function tests on surgical decision-making was analyzed in 196 patients who underwent surgical therapy for colorectal cancer. One hundred and thirteen patients who had preoperative liver scans were compared with 83 patients who did not. No statistically significant difference existed between the liver scan group and the nonscan group in terms of when surgical decision-making occurred. Likewise, the results of the liver scan did not influence when operative decisions were made. The majority of decision-making occurred intraoperatively when ultimate confirmation of the presence or absence of hepatic metastases was made. Presumptive surgical decisions were made preoperatively, but final decisions occurred intraoperatively when all relevant patient data could be correlated. Liver scanning has limited usefulness in the preoperative evaluation of patients with colon cancer as it does not affect decision-making and is much more costly than liver function testing.