Predictors of the efficacy of His bundle pacing in patients with a prolonged PR interval: A stratified analysis of the HOPE-HF randomized controlled trial.

AIMS: The randomized, double-blind, placebo-controlled HOPE-HF trial assessed the benefit of atrio-ventricular (AV) delay optimization delivered using His bundle pacing. It recruited patients with left ventricular ejection fraction ≤40%, PR interval ≥200 ms, and baseline QRS ≤140 ms or right bundle branch block. Overall, there was no significant increase in peak oxygen uptake (VO2max) but there was significant improvement in heart failure specific quality of life. In this pre-specified secondary analysis, we evaluated the impact of baseline PR interval, echocardiographic E-A fusion, and the magnitude of acute high-precision haemodynamic response to pacing, on outcomes. METHODS AND RESULTS: All 167 randomized participants underwent measurement of PR interval, acute haemodynamic response at optimized AV delay, and assessment of presence of E-A fusion. We tested the impact of these baseline parameters using a Bayesian ordinal model on VO2max, quality of life and activity measures. There was strong evidence of a beneficial interaction between the baseline acute haemodynamic response and the blinded benefit of pacing for VO2 (Pr 99.9%), Minnesota Living With Heart Failure (MLWHF) (Pr 99.8%), MLWHF physical limitation score (Pr 98.9%), EQ-5D visual analogue scale (Pr 99.6%), and exercise time (Pr 99.4%). The baseline PR interval and the presence of baseline E-A fusion did not have this reliable ability to predict the clinical benefit of pacing over placebo across multiple endpoints. CONCLUSIONS: In the HOPE-HF trial, the acute haemodynamic response to pacing reliably identified patients who obtained clinical benefit. Patients with a long PR interval (≥200 ms) and left ventricular impairment who obtained acute haemodynamic improvement with AV-optimized His bundle pacing were likely to obtain clinical benefit, consistent across multiple endpoints. Importantly, this gradation can be reliably tested for before randomization, but does require high-precision AV-optimized haemodynamic assessment to be performed.

Prevalence and progression of LV dysfunction and dyssynchrony in patients with new-onset LBBB post TAVR.

BACKGROUND: The impact of new-onset left bundle branch block (N-LBBB) developing after Transcatheter Aortic Valve Replacement (TAVR) on cardiac function and mechanical dyssynchrony is not well defined. METHODS: We retrospectively screened all patients who underwent TAVR in our centre between Oct 2018 and Sept 2021 (n = 409). We identified 38 patients with N-LBBB post-operatively (of which 28 were persistent and 10 were transient), and 17 patients with chronic pre-existent LBBB (C-LBBB). We excluded patients requiring pacing post TAVR. For all groups, we retrospectively analysed stored echocardiograms at 3 time points: before TAVR (T0), early after TAVR (T1, 1.2 ± 1.1 days), and late follow-up (T2, 1.5 ± 0.8 years), comparing LV mass and volumes, indices of LV function (LV ejection fraction, LVEF; global longitudinal strain, GLS), and mechanical dyssynchrony indices (systolic stretch index, severity of septal flash). RESULTS: At baseline (T0), C-LBBB had worse cardiac function, and larger LV volumes and LV mass, compared with patients with N-LBBB. At T1, N-LBBB resulted in mild dyssynchrony and decreased LVEF and GLS. Dyssynchrony progressed at T2 in persistent N-LBBB but not C-LBBB. In both groups however, LVEF remained stable at T2, although individual response was variable. Patients with better LVEF at baseline demonstrated a higher proportion of developing LBBB-induced LV dysfunction at T2. Lack of improvement of LVEF immediately after TAVR predicted deteriorating LVEF at T2. In transient LBBB, cardiac function and most dyssynchrony indices returned to baseline. CONCLUSIONS: N-LBBB after TAVR results in an immediate reduction of cardiac function, in spite of only mild dyssynchrony. When LBBB persists, patients with better cardiac function before TAVR are more likely to have LBBB-induced LV dysfunction after TAVR.

Hypersensitivity Reactions to Components of Cardiac Implantable Electronic Devices and Their Treatment: A Systematic Review.

Background: Hypersensitivity reactions (HSRs) to components of cardiac implantable electronic devices (CIEDs) are rare but difficult to differentiate from device infection. Data on best management strategies of HSRs to CIEDs are lacking. The aims of this systematic review are to summarise the available literature on the aetiology, diagnosis and management of HSR in CIED patients and to provide guidance on best management strategies for these patients. Methods and results: A systematic search for publications on HSR to CIED in PubMed from January 1970 to November 2022 was conducted, resulting in 43 publications reporting on 57 individual cases. The quality of data was low. The mean age was 57 ± 21 years, and 48% of patients were women. The mean time from implant to diagnosis was 29 ± 59 months. Multiple allergens were identified in 11 patients (19%). In 14 cases (25%) no allergen was identified. Blood tests were mostly normal (55%), but eosinophilia (23%), raised inflammatory markers (18%) and raised immunoglobulin E (5%) were also encountered. Symptoms included local reactions, systemic reactions or both in 77%, 21% and 7% of patients, respectively. Explantation of CIED and reimplantation of another CIED coated with a non-allergenic material was usually successful. Use of topical or systemic steroids was associated with high failure rates. Conclusion: Based on the limited data available, the treatment of choice for HSRs to CIEDs is full CIED removal, reassessment of CIED indication and reimplantation of devices coated in non-allergenic materials. Steroids (topical/systemic) have limited efficiency and should not be used. There is an urgent need for further research in this field.

Effects of haemodynamically atrio-ventricular optimized His bundle pacing on heart failure symptoms and exercise capacity: the His Optimized Pacing Evaluated for Heart Failure (HOPE-HF) randomized, double-blind, cross-over trial.

AIMS: Excessive prolongation of PR interval impairs coupling of atrio-ventricular (AV) contraction, which reduces left ventricular pre-load and stroke volume, and worsens symptoms. His bundle pacing allows AV delay shortening while maintaining normal ventricular activation. HOPE-HF evaluated whether AV optimized His pacing is preferable to no-pacing, in a double-blind cross-over fashion, in patients with heart failure, left ventricular ejection fraction (LVEF) ≤40%, PR interval ≥200 ms and either QRS ≤140 ms or right bundle branch block. METHODS AND RESULTS: Patients had atrial and His bundle leads implanted (and an implantable cardioverter-defibrillator lead if clinically indicated) and were randomized to 6 months of pacing and 6 months of no-pacing utilizing a cross-over design. The primary outcome was peak oxygen uptake during symptom-limited exercise. Quality of life, LVEF and patients' holistic symptomatic preference between arms were secondary outcomes. Overall, 167 patients were randomized: 90% men, 69 ± 10 years, QRS duration 124 ± 26 ms, PR interval 249 ± 59 ms, LVEF 33 ± 9%. Neither peak oxygen uptake (+0.25 ml/kg/min, 95% confidence interval [CI] -0.23 to +0.73, p = 0.3) nor LVEF (+0.5%, 95% CI -0.7 to 1.6, p = 0.4) changed with pacing but Minnesota Living with Heart Failure quality of life improved significantly (-3.7, 95% CI -7.1 to -0.3, p = 0.03). Seventy-six percent of patients preferred His bundle pacing-on and 24% pacing-off (p < 0.0001). CONCLUSION: His bundle pacing did not increase peak oxygen uptake but, under double-blind conditions, significantly improved quality of life and was symptomatically preferred by the clear majority of patients. Ventricular pacing delivered via the His bundle did not adversely impact ventricular function during the 6 months.

ST elevation myocardial infarction, or not - This is the question.

We present an artefactual ECG created by a digital ECG-recording machine, caused by deletion of the first 80 ms of the QRS complex immediately following the pacing spike in a patient with complete atrio-ventricular block, biventricular pacing and chronic atrial fibrillation. The artefact was mistaken for inferior ST elevation myocardial infarction and the patient underwent unnecessary urgent coronary angiogram. We are not aware of this particular artefact pattern being previously reported in the literature.

A regularly irregular tachycardia with variable QRS morphologies - What is the mechanism?

We present a complex ECG displaying a combination of atrial tachycardia with Mobitz type I AV block, and right bundle branch block (RBBB) alternans (RBBB alternating with normal QRS conduction) during Wenckebach cycle. A detailed explanation regarding the mechanism of this complex arrhythmia is provided, and the mechanism of bundle branch alternans is reviewed. A unique feature of our case is the added complexity given by the presence of atrial tachycardia and AV Wenckebach, which departs from the previous description of bundle branch alternans during 1:1 AV conduction.

ST elevation in a patient with small bowel occlusion and gastric distension-What is the most likely explanation? A hypothesis generating case report.

We report a case of ST segment elevation and PR depression in inferolateral leads in a patient with small bowel occlusion and gastric distension that disappeared immediately after gastric evacuation. Contrary to prior reports, we believe that these ECG changes do not represent an intrinsic cardiac electrical abnormality, but are likely artefactual. We hypothesise that the accumulated air between the heart, lower limbs and left precordial electrodes result in a significant departure from the simplified assumptions of standard 12 lead ECG analysis (that the electrical activity of the heart can be described by an electrical dipole at a fixed location in an electrical homogeneous sphere) in such a way that the ECG filtering process will not compensate for this bias and will artificially create the ECG pattern described in this report.

Pacemaker implantation in superior vena cava obstruction: Re-canalization, venoplasty, and stenting.

Techniques to overcome challenging venous anatomy have become an increasingly important part of modern day cardiac device implantation. Complete superior vena cava (SVC) obstruction, however, is a rare and serious clinical entity, and consequently there is limited clinical experience in addressing this pathology in the context of transvenous pacemaker implantation. We present the case of a 48-year-old renal transplant patient with sick sinus syndrome and recurrent syncope, who had an upper SVC occlusion and a failed epicardial pacing system. The SVC was re-canalized and stented using techniques derived from chronic total occlusion coronary angioplasty, thus allowing successful implantation of a transvenous pacemaker lead. This case highlights the increased risk of developing central venous occlusion that exists in renal dialysis patients, and demonstrates the benefits of utilizing transferable interventional coronary and radiology techniques to overcome this pathology and facilitate pacemaker implantation. .

Combined subpectoral implantation of a cardioverter defibrillator and breast augmentation surgery in a patient with Emery-Dreifuss muscular dystrophy.

We present the case of a 28-year-old female with Emery-Dreifuss muscular dystrophy and breast hypoplasia, who underwent implantation of a subpectoral defibrillator and bilateral breast augmentation during a single elective procedure at our institution.

Routine issuance of clinical magnets to patients receiving implantable defibrillators: retention of information and appropriateness of use.

BACKGROUND: The application of a clinical magnet over an implantable cardioverter defibrillator (ICD) can be used to suspend tachycardia therapies in patients receiving recurrent or inappropriate shocks. In our institution, they have been routinely issued to patients undergoing ICD implantation during the past 5 years. The purpose of this survey was to investigate how well information concerning their use had been retained, and in what circumstances the magnets had been used. METHODS: We sent a questionnaire to 476 patients, and received a response from 343 (72%). Data was collated using 'Microsoft Excel', cross-referenced against our own pacing database, and analysed using basic statistical methods. RESULTS: 256 (74.6%) patients recalled being issued with a magnet. 48% of these were still in possession of their written information leaflet at the time of survey; 62% felt that they were able to remember when and how to use the magnet-with patients who had received written instructions and verbal reinforcement demonstrating the best recall. 8% of patients had used their magnets and the most common reason for use was multiple or inappropriate shocks. In addition, almost half of the patients who had suffered inappropriate shocks had been able to successfully use their magnets. No cases of harm related to magnet use were identified. CONCLUSIONS: The results of our survey suggest that routinely issuing clinical magnets to ICD patients is a safe and effective practice, and a small but significant number of patients were able to utilise their magnets in clinically important situations.

Can isovolumic acceleration be used in clinical practice to estimate ventricular contractile function? Reproducibility and regional variation of a new noninvasive index.

BACKGROUND: Myocardial acceleration during isovolumic contraction (IVA) has been validated as a relatively load-insensitive noninvasive index of contractility. Its feasibility, reproducibility, and variation between segments have not been studied in detail, and thus its utility in clinical practice has not been established. METHODS: We analyzed myocardial velocity loops (median frame rate 182 s(-1)) from 20 young volunteers (10 men, aged 25.7 +/- 2.9 years), 20 patients with type 2 diabetes (14 men, aged 64.1 +/- 8.5 years), and 20 patients with heart failure (17 men, aged 64.6 +/- 7.7 years). Long-axis IVA was measured in all walls at the annulus and in basal and mid-ventricular segments. Intraobserver reproducibility for 1 observer in all subjects and interobserver reproducibility among 3 observers in 10 subjects from each group were assessed. RESULTS: In control subjects, subjects with diabetes, and subjects with heart failure, the feasibility of measuring IVA was 97%, 89%, and 82%, respectively; intraobserver reproducibility was 12%, 18%, and 30%, respectively (pooled coefficients of variation); and mean interobserver reproducibility was 23%, 21%, and 28%, respectively. IVA was lower in the mid-ventricular segments by 24% to 43% compared with the annulus, and IVA was higher in the right than the left ventricle (P < .001). IVA of the medial mitral annulus discriminated those with heart failure from those with diabetes and controls, and had acceptable intraobserver reproducibility across groups (mean coefficient of variation 13%). CONCLUSION: IVA may be used as a research tool if it is measured at the medial mitral annulus, but its clinical applicability is hampered by low reproducibility, especially in patients with impaired left ventricular function in whom it would otherwise be most useful.

The role of echocardiography in guiding management in dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is a common and malignant condition, which carries a poor long-term prognosis. Underlying disease aetiologies are varied, and often carry specific implications for treatment and prognosis. The role of echocardiography is essential in not only establishing the diagnosis, but also in defining the aetiology, and understanding the pathophysiology. This article therefore explores the pivotal role of echocardiography in the evaluation and management of patients with DCM.

A critical comparison of echocardiographic measurements used for optimizing cardiac resynchronization therapy: stroke distance is best.

AIMS: Dyssynchrony assessment in cardiac resynchronization therapy (CRT) is controversial, and there are no standard protocols for optimizing treatment. We studied the feasibility and reproducibility of several echocardiographic measures to optimize CRT pacemaker settings. We also assessed the utility of 'stroke distance' [left ventricular outflow tract velocity-time integral (LVOT VTI)] in performing this function. METHODS AND RESULTS: Thirty patients underwent the following functional assessments; 6 min walk test distance, peak VO(2) consumption on cardiopulmonary exercise testing (VO(2) peak), quality-of-life scoring, and echocardiography; before and at 3 and 6 months after implantation of the CRT device. At 3 months, patients received LVOT VTI-guided optimization of interventricular (VV) and atrioventricular (AV) delays. The feasibility and reproducibility of each optimization measurement was statistically analysed, and the functional benefits of optimization examined. Left ventricular outflow tract VTI, interventricular mechanical delay (IVMD), and tissue Doppler lateral-septal delay showed good feasibility (>90%), whereas LVOT VTI, IVMD, and the 12-segment tissue Doppler dyssynchrony index showed good reproducibility (coefficient of variation <20%). The most feasible and reproducible measure was LVOT VTI. Our optimization protocol necessitated alteration of AV and/or VV delays in 60% of patients at 3 months and was associated with a 50% improvement in functional responder status between 3 and 6 months. CONCLUSION: Left ventricular outflow tract VTI provides us with a single, direct measure of global LV function which is robust, and easily applicable in routine clinical practice, and which is effective at improving response to CRT.

Blood vessel specific vaso-activity to nitrite under normoxic and hypoxic conditions.

This study uses an organ chamber bioactivity assay to characterise the direct effect of sodium nitrite upon rabbit blood vessels (aorta (Ao), inferior vena cava (IVC) and pulmonary artery (PA)) in a haemoglobin independent/variable oxygen environment. In 95% oxygen constriction to 8g (Ao), 6g (PA) and 4g (IVC) was achieved using 1 microM phenylephrine. The same constriction in 1% oxygen required 3 microM. During 95% oxygen constriction was consistent and sustained for all vessels. However under 1% oxygen PA was quick to constrict but rapidly gave up this tension whereas Ao was slower to constrict but exhibited a more sustained response. Relaxation of each vessel was assessed post constriction using 10 microM sodium nitrite. Results were expressed as a percentage loss in tension compared to the maximum achieved and corrected by controls which received no nitrite. At 95% oxygen PA relaxed greater than Ao (10.04% +/- 2.28% vs. 5.25% +/- 1.51%). IVC response was varied (2.26% +/- 9.43%). At 1% oxygen all vessels relaxed more. However the pattern was reversed with both IVC (14.20% +/- 3.63%) and PA (16.55% +/- 0.93%) relaxing less than Ao (42.20% +/- 5.21%). These results suggest that relatively low concentrations of sodium nitrite can vasodilate blood vessels. This effect is independent of haemoglobin and tissue specific.