Biventricular pacing in hypertrophic obstructive cardiomyopathy: A pilot study

Left Bundle Branch Pacing for Bradycardia in Non-obstructive Hypertrophic Cardiomyopathy Patients: Feasibility, Safety, and Effect

PURPOSE

Left bundle branch pacing (LBBP) is as an innovative physiological pacing approach. The research on LBBP in non-obstructive hypertrophic cardiomyopathy (NOHCM) patients is scarce. This study aimed to assess the feasibility, safety, and effect of LBBP in bradycardia NOHCM patients with permanent pacemaker (PPM) implantation indication.

METHODS

Thirteen consecutive patients with NOHCM who received LBBP were retrospectively enrolled as a hypertrophic cardiomyopathy (HCM) group. Following 1:3 matching, 39 patients without HCM were randomly matched as a control group. Echocardiographic index and pacing parameters were collected.

RESULTS

The successful LBBP was achieved in 96.2% of all cases (50/52), and the success rate of the HCM group was 92.3% (12/13). In the HCM group, the paced QRS duration (from the pacing stimulus to QRS end) was 145.6±20.8 ms. The stimulus to left ventricular activation time (s-LVAT) was 87.4±15.2 ms. In the control group, the paced QRS duration was 139.4±17.2 ms, and the s-LVAT was 79.9±14.1 ms. During the implantation, R-wave sensing and the pacing threshold of the HCM group were significantly higher than the control group (20.2±10.5 vs 12.5±5.9 mV, P < 0.05; 0.8±0.3 vs 0.6±0.2V/0.4 ms, P < 0.05). In addition, the fluoroscopic duration and procedural duration were longer in the HCM group (14.8±8.3 vs 10.3±6.6min, P = 0.07; 131.8±50.5 vs 101.4±41.6 min, P < 0.05). The lead insertion depth was 15±2 mm in the HCM group, and no procedure-related complications occurred. During the 12-month follow-up, pacing parameters remained stable and were of no significance in the two groups. The cardiac function did not deteriorate, and the left ventricular outflow tract gradient (LVOTG) did not increase in the follow-up.

CONCLUSION

LBBP might be feasible and safe for NOHCM patients with conventional bradycardia pacing indication, and there is no deterioration in cardiac function and LVOTG of patients with NOHCM.

Interventions in Hypertrophic Obstructive Cardiomyopathy

Obstructive hypertrophic cardiomyopathy is the most common genetically transmitted cardiomyopathy that is associated with significant morbidity and mortality. Despite contemporary treatments and interventions, the management of patients with obstructive hypertrophic cardiomyopathy remains poorly defined compared with other branches of cardiology. In this review, we discuss established and novel therapeutic interventions in patients with obstructive hypertrophic cardiomyopathy with a focus on percutaneous and surgical strategies including surgical myectomy, mitral valve repair or replacement, percutaneous alcohol septal ablation, pacemaker and cardioverter-defibrillator implantation, septal embolization, radiofrequency endocardial catheter ablation, and percutaneous intramyocardial septal radiofrequency ablation.

Rationale and design of the TRICHAMPION trial: Triple Chamber Pacing in Hypertrophic Obstructive Cardiomyopathy Patients

PURPOSE

Dual-chamber (DDD) pacing has been used for treatment of patients with hypertrophic obstructive cardiomyopathy (HOCM). Due to inconclusive results in prior trials, current guidelines assign DDD pacing a class IIb indication in selected patients. Prior observations indicate that lack of clinical improvement may result from suboptimal effect of DDD pacing with non-physiological AV intervals due to fusion of intrinsic and paced QRS complex.

METHODS

The Triple Chamber Pacing in Hypertrophic Obstructive Cardiomyopathy Patients (TRICHAMPION) trial is a prospective, randomized, single-blinded, multicenter study to investigate the benefit of atrial synchronous biventricular pacing (CRT-P) in highly symptomatic HOCM patients with severe left ventricular outflow tract (LVOT) obstruction who are not candidates for ablative therapies. AV node ablation is used as key tool to optimize AV intervals in patients with QRS fusion. The primary endpoint is the percentage of patients with symptomatic improvement at 12 months, defined as improvement of New York Heart Association functional class, in the Minnesota Living with Heart Failure Questionnaire score and increased cardiopulmonary exercise endurance.

CONCLUSIONS

The aim of the TRICHAMPION trial is to investigate the benefit of optimized atrial synchronous biventricular pacing in absence of QRS fusion in highly symptomatic HOCM patients with severe LVOT obstruction who are not candidates for ablative therapies.

Novel trigenic CACNA1C/DES/MYPN mutations in a family of hypertrophic cardiomyopathy with early repolarization and short QT syndrome

Background

Hypertrophic cardiomyopathy (HCM) patients with early repolarization (ER) pattern are at higher risk of ventricular arrhythmia, yet the genetic background of this situation has not been well investigated. Here we report novel trigenic mutations detected in a Chinese family of obstructive HCM with ER and short QT syndrome (SQTS).

Methods

Proband and family members underwent detailed medical assessments. DNAs were extracted from peripheral blood leukocytes for genetic screening with next generation method. The functional characterization of the mutation was conducted in TSA201 cells with patch-clamp experiment.

Results

The proband was a 52-year-old male who had a ER pattern ECG in inferioral-lateral leads with atrioventricular block and QTc of 356 ms. He also suffered from severe left ventricular hypertrophy and dysfunction. Targeted sequencing revealed trigenic mutations: c.700G>A/p.E234K in DES, c.2966G>A/p.R989H in MYPN, and c.5918G>C/p.R1973P in CACNA1C. All mutations were also detected in his daughter with ER and mild myocardium hypertrophy. The CACNA1C-R1973P mutation caused significant reduction (68.4%) of I_Ca compared to CACNA1C-WT (n = 14 and 14, P < 0.05). The computer modeling showed that all 3 mutations were highly disease-causing. The proband received the CRT-D (cardiac resynchronizing therapy) implantation, which lowered the left ventricular outflow tract gradient (LVOTG, 124 mmHg pre vs. 27 mmHg post) and restored the LV function (LVEF 40% pre vs. 63% post).

Conclusions

The study reveals a novel CACNA1C mutation underlying the unique ER pattern ECGs with SQTS. It also shows the rare trigenic mutations are the pathogenic substrates for the complicated clinical manifestation in HCM patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1180-1) contains supplementary material, which is available to authorized users.

Update on hypertrophic cardiomyopathy and a guide to the guidelines

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disorder, affecting 1 in 500 individuals worldwide. Existing epidemiological studies might have underestimated the prevalence of HCM, however, owing to limited inclusion of individuals with early, incomplete phenotypic expression. Clinical manifestations of HCM include diastolic dysfunction, left ventricular outflow tract obstruction, ischaemia, atrial fibrillation, abnormal vascular responses and, in 5% of patients, progression to a 'burnt-out' phase characterized by systolic impairment. Disease-related mortality is most often attributable to sudden cardiac death, heart failure, and embolic stroke. The majority of individuals with HCM, however, have normal or near-normal life expectancy, owing in part to contemporary management strategies including family screening, risk stratification, thromboembolic prophylaxis, and implantation of cardioverter-defibrillators. The clinical guidelines for HCM issued by the ACC Foundation/AHA and the ESC facilitate evaluation and management of the disease. In this Review, we aim to assist clinicians in navigating the guidelines by highlighting important updates, current gaps in knowledge, differences in the recommendations, and challenges in implementing them, including aids and pitfalls in clinical and pathological evaluation. We also discuss the advances in genetics, imaging, and molecular research that will underpin future developments in diagnosis and therapy for HCM.

Dyssynchronization reduces dynamic obstruction without affecting systolic function in patients with hypertrophic obstructive cardiomyopathy: a pilot study

Dyssynchrony from biventricular pacing (BiV) can reduce dynamic obstruction in hypertrophic obstructive cardiomyopathy (HOCM), but its consequences on the left ventricular (LV) systolic function are unknown. We evaluate changes in LV systolic function and assess the effectiveness of BiV in HOCM. Thirteen patients with HOCM (55 [33/75] years, five males) received a BiV device and underwent 2D transthoracic echocardiography before the implantation and at 12 months follow-up. Global longitudinal and radial strain, and the timing of segmental displacement curves were measured by commercial speckle-tracking software to assess LV systolic function and dyssynchrony. Peak gradient in the LV outflow tract (LVOT) significantly decreased from 80 [51/100] to 30 [5/66] mmHg (p = 0.005). LV global strain was preserved from baseline to follow-up: 35.1 [20.2/43.8] % vs. 32.6 [27.1/44.1] %, p = NS (radial), and -16.6 [-19.1/-14.4] % vs. -15.7 [-17.0/-14.2] %, p = NS (longitudinal). Dyssynchrony analysis using displacement curves showed inversion of wall motion timing with earlier displacement of the lateral wall at follow-up only in patients with reduction in LVOT gradient. BiV reduces LVOT obstruction in patients with HOCM when dyssynchronization of LV motion and inversion of the timing of LV wall activation are reached. Notably, this does not lead to further deterioration of LV systolic function at mid-term follow-up.

Wall Thickness, Pulmonary Hypertension, and Diastolic Filling Abnormalities Predict Response to Postoperative Biventricular Pacing

OBJECTIVE

Post-cardiopulmonary bypass biventricular pacing improves hemodynamics but without clearly defined predictors of response. Based on preclinical studies and prior observations, it was suspected that diastolic dysfunction or pulmonary hypertension is predictive of hemodynamic benefit.

DESIGN

Randomized controlled study of temporary biventricular pacing after cardiopulmonary bypass.

SETTING

Single-center study at university-affiliated tertiary care hospital.

INTERVENTIONS

Patients who underwent bypass with preoperative ejection fraction ≤40% and QRS duration ≥100 ms or double-valve surgery were enrolled. At 3 time points between separation from bypass and postoperative day 1, pacing delays were varied to optimize hemodynamics.

PARTICIPANTS

Data from 43 patients were analyzed.

MEASUREMENTS AND MAIN RESULTS

Cardiac output and arterial pressure were measured under no pacing, atrial pacing, and biventricular pacing. Preoperative echocardiograms and pulmonary artery catheterizations were reviewed, and measures of both systolic and diastolic function were compared to hemodynamic response. Early after separation, improvement in cardiac output was positively correlated with pulmonary vascular resistance (R(2) = 0.97, p<0.001), ventricle wall thickness (R(2) = 0.72, p = 0.002)), and E/e', a measure of abnormal diastolic ventricular filling velocity (R(2) = 0.56, p = 0.04). Similar trends were seen with mean arterial pressure. QRS duration and ejection fraction did not correlate significantly with improvements in hemodynamics.

CONCLUSIONS

There may be an effect of biventricular pacing related to amelioration of abnormal diastolic filling patterns rather than electrical resynchronization in the postoperative state.

Basal infarct location but not larger infarct size is associated with a successful outcome after alcohol septal ablation in patients with hypertrophic obstructive cardiomyopathy: a cardiovascular magnetic resonance imaging study

Alcohol septal ablation (ASA) is successful in most but not in all patients with obstructive hypertrophic cardiomyopathy (HCM). We therefore sought to investigate the relation between infarct location versus infarct size with outcome after ASA in patients with obstructive HCM. Baseline characteristics, procedural characteristics, and cardiovascular magnetic resonance findings at baseline and 4-6 month follow-up after ASA were analysed in 47 patients with obstructive HCM in a single-center retrospective study. Infarct size was determined using late gadolinium enhancement. Infarct location was divided into "basal infarction" and "distal infarction" based on an optimal cut-of value of the distance from the basal septum to the beginning of the infarction. A "successful" outcome was defined as 80% reduction of the invasive gradient with a post-procedural gradient of <10 mmHg. Basal infarctions (n = 31) compared to distal infarctions (n = 16) were associated with successful outcome (100 vs. 38%, P < 0.001). Larger infarct size (n = 20) compared to smaller infarct size (n = 27) was not associated with successful outcome (75 vs. 82%, P = 0.72). A more distal location of the infarction, was the only predictor of a less successful outcome (odds ratio 0.76, 95% confidence interval 0.54-0.98, P = 0.03). Basal versus distal infarctions were also associated with a lower provoked gradient at late (2.6 ± 2.2 years) follow-up (11 (6-20) vs. 27 (12-94) mmHg, P = 0.01). Basal infarctions were associated with a successful outcome after ASA. A larger infarct size was not associated with a better outcome.

Hypertrophic cardiomyopathy: a review

Hypertrophic cardiomyopathy (HCM) is a global disease with cases reported in all continents, affecting people of both genders and of various racial and ethnic origins. Widely accepted as a monogenic disease caused by a mutation in 1 of 13 or more sarcomeric genes, HCM can present catastrophically with sudden cardiac death (SCD) or ventricular arrhythmias or insidiously with symptoms of heart failure. Given the velocity of progress in both the fields of heart failure and HCM, we present a review of the approach to patients with HCM, with particular attention to those with HCM and the clinical syndrome of heart failure.

Optimized pacing mode for hypertrophic cardiomyopathy: Impact of ECG fusion during pacing

BACKGROUND

Electrocardiographic (ECG) fusion with intrinsic QRS could reduce the benefit of atrial synchronous biventricular pacing (AS-BiVP) in patients with hypertrophic obstructive cardiomyopathy (HOCM).

OBJECTIVES

The purpose of this study was to assess the benefit of AS-BiVP and the influence of ECG fusion for reduction of left ventricular outflow tract gradient (LVOTG) in these patients.

METHODS

Twenty-one symptomatic HOCM patients with severe LVOTG were included. Twelve patients were evaluated retrospectively for the prevalence of fusion and its influence on outcomes after AS-BiVP. Eleven patients (2 of the first population were also evaluated retrospectively) were prospectively included to evaluate the benefit of performing atrioventricular node ablation (AVNA) to achieve full ventricular capture if fusion was present during AS-BiVP.

RESULTS

Seven of the first 12 patients (58%) had ECG fusion. After 54 ± 24 months of AS-BiVP, the presence of fusion was associated with lower values for reduction of resting, dynamic LVOTG and New York Heart Association (NYHA) class. In the prospectively evaluated patients, after 12 months of follow-up, resting LVOTG decreased from 98 ± 39 to 39 ± 24 mm Hg (P = .008); dynamic LVOTG decreased from 112 ± 38 to 60 ± 24 mm Hg (P = .013); NYHA class decreased from 2.8 ± 0.4 to 1.7 ± 0.6 (P = .014); endurance time during constant work rate cycling exercise (80% of peak oxygen consumption) increased from 399 ± 148 to 691 ± 249 seconds (P = .046); quality of life improved from 46 ± 22 to 22 ± 20 points (P = .02); and brain natriuretic peptide levels decreased from 318 ± 238 to 152 ± 118 pg/mL (P = .09). Eight of the 11 prospectively evaluated patients (73%) needed AVNA, which further decreased LVOTG from 108 ± 40 mm Hg at baseline to 89 ± 29 mm Hg after BiVP to 54 ± 22 mm Hg after AVNA (P = .003).

CONCLUSION

As-BiVP that ensures no ECG fusion, by means of AVNA when needed, appears to be the optimal pacing mode in HOCM patients.

Biventricular / left ventricular pacing in hypertrophic obstructive cardiomyopathy: an overview

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant inherited genetic disease characterized by compensatory pathological left ventricle (LV) hypertrophy due to sarcomere dysfunction. In an important proportion of patients with HCM, the site and extent of cardiac hypertrophy results in severe obstruction to LV outflow tract (LVOT), contributing to disabling symptoms and increasing the risk of sudden cardiac death (SCD). In patients with progressive and/or refractory symptoms despite optimal pharmacological treatment, invasive therapies that diminish or abolish LVOT obstruction relieve heart failure-related symptoms, improve quality of life and could be associated with long-term survival similar to that observed in the general population. The gold standard in this respect is surgical septal myectomy, which might be supplementary associated with a reduction in SCD. Percutaneous techniques, particularly alcohol septal ablation (ASA) and more recently radiofrequency (RF) septal ablation, can achieve LVOT gradient reduction and symptomatic benefit in a large proportion of HOCM patients at the cost of a supposedly limited septal myocardial necrosis and a 10-20% risk of chronic atrioventricular block. After an initial period of enthusiasm, standard DDD pacing failed to show in randomized trials significant LVOT gradient reductions and objective improvement in exercise capacity. However, case reports and recent small pilot studies suggested that atrial synchronous LV or biventricular (biV) pacing significantly reduce LVOT obstruction and improve symptoms (acutely as well as long-term) in a large proportion of severely symptomatic HOCM patients not suitable to other gradient reduction therapies. Moreover, biV/LV pacing in HOCM seems to be associated with significant LV reverse remodelling.

Developments in heart failure 2011

Last year, the authors reviewed all studies in the field of heart failure (HF) published in the year 2010. Another year of exciting new developments has gone by and several important papers have been published. Summarized are the important studies published in the year 2011 that may be a useful review for cardiologists and other health care professionals who care for patients with HF.