Long-term results of dual-chamber (DDD) pacing in obstructive hypertrophic cardiomyopathy. Evidence for progressive symptomatic and hemodynamic improvement and reduction of left ventricular hypertrophy

Ventricular Septal Myectomy for Obstructive Hypertrophic Cardiomyopathy (Analysis Spanning 60 Years Of Practice): AJC Expert Panel

Surgical myectomy remains the time-honored primary treatment for hypertrophic cardiomyopathy patients with drug refractory limiting symptoms due to LV outflow obstruction. Based on >50 years experience, surgery reliably reverses disabling heart failure by permanently abolishing mechanical outflow impedance and mitral regurgitation, with normalization of LV pressures and preserved systolic function. A consortium of 10 international currently active myectomy centers report about 11,000 operations, increasing significantly in number over the most recent 15 years. Performed in experienced multidisciplinary institutions, perioperative mortality for myectomy has declined to 0.6%, becoming one of the safest currently performed open-heart procedures. Extended myectomy relieves symptoms in >90% of patients by ≥ 1 NYHA functional class, returning most to normal daily activity, and also with a long-term survival benefit; concomitant Cox-Maze procedure can reduce the number of atrial fibrillation episodes. Surgery, preferably performed in high volume clinical environments, continues to flourish as a guideline-based and preferred high benefit: low treatment risk option for adults and children with drug refractory disabling symptoms from obstruction, despite prior challenges: higher operative mortality/skepticism in 1960s/1970s; dual-chamber pacing in 1990s, alcohol ablation in 2000s, and now introduction of strong negative inotropic drugs potentially useful for symptom management.

The Initial Experience of Left Bundle Branch Area Pacing in Patients with Hypertrophic Cardiomyopathy

PURPOSE

Whether Left bundle branch area pacing (LBBAP) could be achieved in patients with hypertrophic cardiomyopathy (HCM) requiring ventricular pacing remains unknown. The present study aimed to investigate the feasibility and effect of LBBAP in HCM.

METHODS

Patients with HCM who underwent LBBAP were recruited from November 2018 to September 2021. Clinical characteristics, echocardiographic, and pacing parameters were prospectively collected at baseline and during follow-up.

RESULTS

Eleven consecutive HCM patients who attempted LBBAP were included (mean age 64.0±8.7 years, female 45.5%, mean interventricular septum 16.7mm). The success rate of LBBAP was 36.4% (4/11) and the reason for failed LBBAP in other 7 HCM patients was the inability to screw the lead into the deep septum or capture the left bundle branch. Patients with successful LBBAP had significantly narrower QRS duration than those with failed (118.0 ± 3.7 ms vs. 140.9 ± 9.4 ms, p = 0.01) while the capture thresholds, sensing amplitudes, and pacing impedances were similar. Successful cases presented with less positive late gadolinium enhancement (25.0% vs. 71.4%, p = 0.02) and thinner interventricular thickness (14.5 ± 1.0 mm vs. 18.0 ± 2.5 mm, p = 0.02) when compared with failed cases. Pacing parameters remained stable and no procedure-related complications occurred during a mean follow-up of 8.9 ± 7.3 months.

CONCLUSION

LBBAP may be successfully achieved in less than half of HCM patients due to thick interventricular septum and heavy burden of myocardial fibrosis. Pacing strategies should be cautiously considered in patients with HCM. This article is protected by copyright. All rights reserved.

Review of Contemporary Invasive Treatment Approaches and Critical Appraisal of Guidelines on Hypertrophic Obstructive Cardiomyopathy: State-of-the-Art Review

BACKGROUND

Hypertrophic obstructive cardiomyopathy (HOCM) is a heterogeneous disease with different clinical presentations, albeit producing similar dismal long-term outcomes if left untreated. Several approaches are available for the treatment of HOCM; e.g., alcohol septal ablation (ASA) and surgical myectomy (SM). The objectives of the current review were to (1) discuss the place of the standard invasive treatment modalities (ASA and SM) for HOCM; (2) summarize and compare novel techniques for the management of HOCM; (3) analyze current guidelines addressing HOCM management; and (4) offer suggestions for the treatment of complex HOCM presentations.

METHODS

We searched the literature and attempted to gather the most relevant and impactful available evidence on ASA, SM, and other invasive means of treatment of HOCM. The literature search yielded thousands of results, and 103 significant publications were ultimately included.

RESULTS

We critically analyzed available guidelines and provided context in the setting of patient selection for standard and novel treatment modalities. This review offers the most comprehensive analysis to-date of available invasive treatments for HOCM. These include the standard treatments, SM and ASA, as well as novel treatments such as dual-chamber pacing and radiofrequency catheter ablation. We also account for complex pathoanatomic presentations and current guidelines to offer suggestions for tailored care of patients with HOCM. Finally, we consider promising future therapies for HOCM.

CONCLUSIONS

HOCM is a heterogeneous disease associated with poor outcomes if left untreated. Several strategies for treatment of HOCM are available but patient selection for the procedure is crucial.

Haemodynamic collapse immediately after transcatheter aortic valve implantation due to dynamic intraventricular gradient: a case report and review of the literature

Background

Dynamic intraventricular obstruction after transcatheter aortic valve implantation (TAVI) has been previously reported. There is a risk of haemodynamic collapse in the case of left ventricular outflow tract (LVOT) obstruction due to systolic anterior motion (SAM) of the mitral valve.

Case summary

An 83-year-old woman with aortic stenosis (AS) was referred to our hospital for TAVI. Transthoracic echocardiography revealed a severely calcified aortic valve with a peak velocity of 6.3 m/s across the valve. Acceleration of blood flow (peak velocity 2.6 m/s) at the LVOT due to a septal bulge was also seen. Transfemoral TAVI was performed, and a 29 mm Evolut PRO was implanted under general anaesthesia. After the implantation, a complete atrioventricular block with junctional rhythm developed, and refractory hypotension occurred immediately. Transoesophageal echocardiography revealed LVOT obstruction due to SAM of the mitral valve associated with severe mitral regurgitation (MR), which was not observed preoperatively. Fluid infusion and catecholamine administration were not effective. However, after performing temporary pacing from the right ventricular (RV) apex, the LVOT obstruction and severe MR improved. Her haemodynamics stabilized, and we could complete the procedure. A dual-chamber permanent pacemaker with beta-blocker administration as a longer-term treatment further improved the LVOT obstruction. The patient was finally discharged to a rehabilitation hospital.

Discussion

Alertness and recognition of potential LVOT obstruction after TAVI are important. Pacing from the RV apex, as well as dual-chamber pacing, comprise a less invasive and feasible therapeutic option in such cases.

Right ventricular pacing for hypertrophic obstructive cardiomyopathy: meta-analysis and meta-regression of clinical trials

Aims

Right ventricular pacing for left ventricular outflow tract gradient reduction in hypertrophic obstructive cardiomyopathy remains controversial. We undertook a meta-analysis for echocardiographic and functional outcomes.

Methods and results

Thirty-four studies comprising 1135 patients met eligibility criteria. In the four blinded randomized controlled trials (RCTs), pacing reduced gradient by 35% [95% confidence interval (CI) 23.2–46.9, P < 0.0001], but there was only a trend towards improved New York Heart Association (NYHA) class [odds ratio (OR) 1.82, CI 0.96–3.44; P = 0.066]. The unblinded observational studies reported a 54.3% (CI 44.1–64.6, P < 0.0001) reduction in gradient, which was a 18.6% greater reduction than the RCTs (P = 0.0351 for difference between study designs). Observational studies reported an effect on unblinded NYHA class at an OR of 8.39 (CI 4.39–16.04, P < 0.0001), 450% larger than the OR in RCTs (P = 0.0042 for difference between study designs). Across all studies, the gradient progressively decreased at longer follow durations, by 5.2% per month (CI 2.5–7.9, P = 0.0001).

Conclusion

Right ventricular pacing reduces gradient in blinded RCTs. There is a non-significant trend to reduction in NYHA class. The bias in assessment of NYHA class in observational studies appears to be more than twice as large as any genuine treatment effect.

Permanent Pacing in a Patient with Left Ventricular Mid-Cavity Obstruction and Apical Aneurysm

Hypertrophic cardiomyopathy with left ventricular (LV) mid-cavity obstruction and LV apical aneurysm is associated with high morbidity and mortality rates. However, consensus is lacking on the treatment modality for LV mid-cavity obstruction and LV apical aneurysm. Here, we report a case of reduced LV mid-cavity pressure gradient and symptoms, treated using permanent pacing. The effect of permanent pacing on pressure gradient and symptoms lasted for 4 years. As pacing is relatively non-invasive compared to surgical therapy, permanent pacing is a good option, especially in the elderly patients with LV mid-cavity obstruction and apical aneurysm.

Short atrioventricular delay pacing therapy in young and old patients with hypertrophic obstructive cardiomyopathy: good long-term results and a low need for reinterventions

Aims

Examination of long-term results following different treatments in hypertrophic obstructive cardiomyopathy (HOCM) in a complete geographical cohort.

Methods and results

HOCM patients attending during 2002–13 in all 10 hospitals in the West Götaland Region, Sweden, were identified (n = 251), follow-up 14.4 (±8.9) years (mean ± SD), 121 managed medically, 42 treated with myectomy and 88 with short atrioventricular (AV) delay pacing as first interventional procedure. Post-intervention follow-up was 12.9 ± 8.7 years and 12.2 ± 5.0 years, respectively. Both intervention treatments improved New York Heart Association (NYHA) class and outflow gradients significantly. Patients treated with pacing were older (median age 64 vs. 43 years, P < 0.001). Freedom from disease-related death post-procedure at 5, 10, and 20 years were 93%, 80%, 56% vs. 93%, 93%, 57% in pacing and myectomy groups, respectively (log-rank P = 0.43). Survival after diagnosis was not different in patients just treated conservatively (P = 0.51 pacing/conservative; P = 0.39 myectomy/conservative). Reintervention for outflow gradients in patients ≥18 years at procedure occurred in 3.5% in pacing group and 15.6% in myectomy group (P = 0.007). Pacing therapy was equally effective in patients aged 13–64 years (n = 44), as in patients ≥65 years (n = 44): resting gradient pre-procedure and at last follow-up were median (IQR) 65 (71) and 12 (20) mmHg for <65 year-olds (P < 0.001), and 75 (64) and 14 (38) mmHg, respectively, for ≥65 year-olds (P < 0.001). New York Heart Association class improved significantly in both age ranges to 1.6 ± 0.6 and 1.8 ± 0.7, respectively (P < 0.001; P < 0.001).

Conclusion

Short AV delay pacing provided lasting satisfactory relief of symptoms and outflow obstruction in the majority of patients, with low risk of requiring reintervention. Our findings support the view that pacing therapy should be considered a valid option to treat patients with HOCM.

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.

Interregional electro-mechanical heterogeneity in the rabbit myocardium

BACKGROUND

Increased electrical heterogeneity has been causatively linked to arrhythmic disorders, yet the knowledge about physiological heterogeneity remains incomplete. This study investigates regional electro-mechanical heterogeneities in rabbits, one of the key animal models for arrhythmic disorders.

METHODS AND FINDINGS

7 wild-type rabbits were examined by phase-contrast magnetic resonance imaging in vivo to assess cardiac wall movement velocities. Using a novel data-processing algorithm regional contraction-like profiles were calculated. Contraction started earlier and was longer in left ventricular (LV) apex than base. Patch clamp recordings showed longer action potentials (AP) in LV apex compared to the base of LV, septum, and right ventricle. Western blots of cardiac ion channels and calcium handling proteins showed lower expression of Cav1.2, KvLQT1, Kv1.4, NCX and Phospholamban in LV apex vs. base. A single-cell in silico model integrating the quantitative regional differences in ion channels reproduced a longer contraction and longer AP in apex vs. base.

CONCLUSIONS

Apico-basal electro-mechanical heterogeneity is physiologically present in the healthy rabbit heart. An apico-basal electro-mechanical gradient exists with longer APD and contraction duration in the apex and associated regionally heterogeneous expression of five key proteins. This pattern of apical mechanical dominance probably serves to increase pumping efficiency.

Hypertrophic obstructive cardiomyopathy

Hypertrophic obstructive cardiomyopathy is an inherited myocardial disease defined by cardiac hypertrophy (wall thickness ≥15 mm) that is not explained by abnormal loading conditions, and left ventricular obstruction greater than or equal to 30 mm Hg. Typical symptoms include dyspnoea, chest pain, palpitations, and syncope. The diagnosis is usually suspected on clinical examination and confirmed by imaging. Some patients are at increased risk of sudden cardiac death, heart failure, and atrial fibrillation. Patients with an increased risk of sudden cardiac death undergo cardioverter-defibrillator implantation; in patients with severe symptoms related to ventricular obstruction, septal reduction therapy (myectomy or alcohol septal ablation) is recommended. Life-long anticoagulation is indicated after the first episode of atrial fibrillation.

Treating a Structural Heart Disease Using a Non-structural Approach: Role of Cardiac Pacing in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease characterized by a thickened non-dilated ventricle in the absence of another cardiac or systemic condition. Its most important hemodynamic consequence is left ventricular outflow tract (LVOT) obstruction. The primary management strategy of this condition is surgical septal myectomy, but an acceptable alternative treatment in patients who are not suitable for (or who refuse) surgery is alcohol septal ablation (ASA). However, in patients with unfavorable coronary anatomy which precludes ASA (i.e. absence of major septal perforator branch of the left anterior descending (LAD) artery), another reasonable option is dual chamber pacemaker implantation to decrease LVOT outflow gradient. A 77-year-old female, known hypertensive, diabetic with a history of coronary artery disease, presented with 1-week history of worsening chest pain and shortness of breath. She was admitted as a case of acute coronary syndrome and pneumonia. On workup, 2DED revealed hypertrophic obstructive cardiomyopathy (HOCM) with a demonstrated systolic anterior motion (SAM) of the mitral valve with a peak instantaneous gradient of 194 mm Hg across the basal LV cavity. The patient refused surgical myectomy, and ASA was the preferred treatment option. On coronary angiography, there was an incidental finding of absent major septal perforator branch of the LAD coronary artery, rendering her unsuitable for septal ablation. She was referred to electrophysiology for evaluation. She underwent dual chamber pacemaker implantation and documented significant decrease in the peak instantaneous gradient from 194 to 37 mm Hg, with complete obliteration of SAM and improvement in overall wall motion. She remained stable and asymptomatic after pacemaker insertion until her recent outpatient follow-up (1 year after implantation). We present a case of HCM with congenitally absent major septal perforator branch coronary artery treated with dual chamber pacemaker implantation. To our knowledge, this is the first reported angiographically absent first (major) septal perforator coronary anatomy in the setting of HCM, and also the first description of dual chamber pacemaker implantation to relieve the LVOT obstruction. Although the role of dual chamber pacing has become limited in HCM because surgical myectomy and septal ablation have resulted in better decrease in LV outflow gradient and symptom improvement, this modality remains essential and may still be considered as the treatment strategy-of-choice in patients who are unsuitable for surgical myectomy and ASA.

Intestinal angina in a patient with hypertrophic obstructive cardiomyopathy: a case report

Background

Intestinal angina is characterized by recurrent postprandial abdominal pain and anorexia. Commonly, these symptoms are caused by severe stenosis of at least two vessels among the celiac and mesenteric arteries. However, intestinal perfusion is affected not only by the degree of arterial stenosis but also by systemic perfusion. We experienced a unique case of intestinal angina caused by relatively mild stenosis of the abdominal arteries complicated with hypertrophic obstructive cardiomyopathy.

Case presentation

We report an 86-year old Japanese man with hypertrophic obstructive cardiomyopathy and advanced atrioventricular block who was diagnosed with intestinal angina. Computed tomography showed mild stenosis of the celiac artery and severe stenosis of the inferior mesenteric artery, and these lesions were relatively mild compared with other reports. A dual-chamber pacemaker with right ventricular apical pacing was implanted to improve the obstruction of the left ventricular outflow tract. After implantation, the patient’s abdominal symptoms diminished markedly, and improvement of the left ventricular outflow tract obstruction was observed.

Conclusions

Although intestinal angina is generally defined by severe stenosis of at least two vessels among the celiac and mesenteric arteries, the present case suggests that hemodynamic changes can greatly affect intestinal perfusion and induce intestinal angina in the presence of mild stenosis of the celiac and mesenteric arteries.

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.

Sequential Atrioventricular Pacing in Patients With Hypertrophic Cardiomyopathy: An 18-year Experience

INTRODUCTION AND OBJECTIVES

Controversy persists regarding the role of sequential atrioventricular pacing in patients with obstructive hypertrophic cardiomyopathy and disabling symptoms. The aim of this study was to evaluate the effect of pacing on symptoms, dynamic gradient, and left ventricular function in patients with hypertrophic cardiomyopathy.

METHODS

From 1991 to 2009, dual-chamber pacemakers were implanted in 82 patients with obstructive hypertrophic cardiomyopathy and disabling symptoms despite optimal medical therapy. Sequential pacing was performed with a short atrioventricular delay. Clinical and echocardiographic parameters were measured before and immediately after implantation and after a long follow-up (median, 8.5 years [range, 1-18 years]).

RESULTS

The New York Heart Association functional class was immediately reduced after pacemaker implantation in 95% of patients (P < .0001), and this improvement was maintained until the final follow-up in 89% (P = .016). The gradient was significantly reduced after implantation (94.5 ± 36.5 vs 46.4 ± 26.7mmHg; P < .0001) and at final follow-up (94.5 ± 36.5 vs 35.9 ± 24.0mmHg; P < .0001). Mitral regurgitation permanently improved in 52% of the patients (P < .0001). There were no differences in ventricular thickness or diameters, ejection fraction, or diastolic function.

CONCLUSIONS

Sequential pacing in selected patients with obstructive hypertrophic cardiomyopathy improves functional class and reduces dynamic gradient and mitral regurgitation immediately after pacemaker implantation and at final follow-up. Prolonged ventricular pacing has no negative effects on systolic or diastolic function in these patients.

Atrioventricular Sequential Pacing for Hypertrophic Cardiomyopathy During Liver Transplantation

Hypertrophic cardiomyopathy is a myocardial disorder that carries an increased risk of morbidity and mortality during liver transplantation. We describe the use of atrioventricular sequential pacing, placed preoperatively, to assist with intraoperative management of a patient with severe refractory hypertrophic cardiomyopathy undergoing orthotopic piggyback liver transplantation. We discuss the pathogenesis and treatment of this infrequent but serious comorbidity.

Abnormal left ventricular contraction sequence in hypertrophic cardiomyopathy patients: first description of hypersynchrony and invert synchrony

The aim of this study was to compare left ventricular contraction sequence in patients with hypertrophic cardiomyopathy (HCM) and healthy controls. Normal left ventricular contraction sequence in healthy controls exhibits an apex-to-base delay (ABD) contributing to efficient cardiac mechanics (physiologic asynchrony). Echocardiographic data from 20 controls and 40 HCM patients were prospectively analyzed. Endocardial longitudinal and circumferential strains and ABD were measured using custom-built software. HCM patients had increased circumferential (-36.4 ± 6.0 vs. -32.9 ± 5.0, p < 0.01) and decreased longitudinal (-19.3 ± 6.4 vs. -23.4 ± 5.7, p < 0.01) strains. In controls, physiologic ABD was observed (35.7 ± 18.1 ms). This delay was reduced in HCM patients (5.5 ± 22.7 ms, p < 0.01 vs. controls). There was no interaction between ABD and common clinical or echocardiographic parameters in the HCM population. Left ventricular contraction sequence can be modified in HCM patients, with the loss of the physiologic ABD. This phenomenon is independent from commonly measured parameters.

Current status and future perspectives on alcohol septal ablation for hypertrophic obstructive cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiac disease. Patients may present with a wide variety of symptoms, ranging from relatively asymptomatic to heart failure, recurrent syncope, angina, or sudden death. Once diagnosed, a thorough clinical, anatomic and physiologic assessment should be undertaken. Treatment options include both pharmacologic and invasive therapies, with a goal to reduce symptoms and possibly extend longevity. Traditionally, the "gold standard" for treating severe obstructive HCM has been ventricular septal myotomy-myomectomy. Since its introduction in 1994, alcohol septal ablation (ASA) has emerged as an acceptable alternative in patients who meet strict anatomic criteria, and has been supported in recent guidelines. We review the indications, technique, competency requirements, alternatives, outcomes, complications, and future directions of ASA.

Comparison of long-term effect of dual-chamber pacing and alcohol septal ablation in patients with hypertrophic obstructive cardiomyopathy

Introduction. Nonpharmacological treatment of patients with hypertrophic obstructive cardiomyopathy (HOCM) comprises surgical myectomy (SME), alcohol septal ablation (ASA), and dual-chamber (DDD) pacing. The aim of the study was to compare the long-term effect of DDD pacing and ASA in symptomatic HOCM patients. Patients and Methods. We evaluated retrospective data from three cardiocenters; there were 24 patients treated with DDD pacing included and 52 treated with ASA followed for 101 ± 49 and 87 ± 23 months, respectively. Results. In the group treated with DDD pacing, the left ventricle outflow tract gradient (LVOTG) decreased from 82 ± 44 mmHg to 21 ± 21 mmHg, and NYHA class improved from 2.7 ± 0.5 to 2.1 ± 0.6 (both P < 0.001). In the ASA-treated group, a decline in LVOTG from 73 ± 38 mmHg to 24 ± 26 mmHg and reduction in NYHA class from 2.8 ± 0.5 to 1.7 ± 0.8 were observed (both P < 0.001). The LVOTG change was similar in both groups (P = 0.264), and symptoms were more affected by ASA (P = 0.001). Conclusion. ASA and DDD pacing were similarly effective in reducing LVOTG. The symptoms improvement was more expressed in patients treated with ASA.

Radiofrequency catheter ablation of the accessory pathway adversely affected the left ventricular outflow tract pressure gradient in a patient with hypertrophic obstructive cardiomyopathy

Although hypertrophic cardiomyopathy (HCM) with an accessory pathway is encountered in clinical practice, there is little evidence of a coherent strategy for ablation of the accessory pathway in patients with HCM. We present the case of a 61-year-old man who had type B Wolff-Parkinson-White (WPW) syndrome with hypertrophic obstructive cardiomyopathy (HOCM). Due to paroxysmal atrial fibrillation, he underwent radiofrequency catheter ablation of the accessory pathway located in the right postero-lateral wall to prevent secondary symptomatic events. His LV dyssynchrony improved after the procedure, but the degree of the LV outflow tract (LVOT) pressure gradient was increased. To stabilize the LVOT pressure gradient, he needed additional medications. This case shows that patients with HOCM should be carefully evaluated before making a decision concerning ablation of the accessory pathway.

Long-term follow-up impact of dual-chamber pacing on patients with hypertrophic obstructive cardiomyopathy

BACKGROUND

Pacing has been proposed as a treatment for patients with hypertrophic obstructive cardiomyopathy (HOCM), but there are few studies with long-term follow-up. We evaluated the long-term effects of dual-chamber pacing therapy for patients with HOCM, and to identify the most prognosis-specific factors for predicting outcome in such treating methods.

METHODS

A total of 37 HOCM patients implanted with dual-chamber pacemakers were enrolled consecutively and followed-up. Thirty-seven cases were followed for 1 year, 26 cases for 2 years, 10 cases for 3 years, and eight cases for 4 years. At each annual point of follow-up after pacemaker implantation, the pacing frequency, pacing threshold, impedance, atrioventricular delay, and cumulative percentage of atrial and ventricular pacing were tested, respectively. In addition, left atrial dimension (LAD), left ventricular end diastolic dimension (LVEDd), left ventricular posterior wall thickness (LVPW), interventricular septum thickness (IVS), left ventricular outflow tract dimension (LVOTd), peak velocity of left ventricular outflow tract (VLVOT), left ventricular outflow tract pressure gradient (LVOTPG), left ventricular ejection fraction (LVEF), and pulmonary artery systolic pressure (PASP) were measured. Mitral valve systolic anterior motion (SAM) was also observed. Pacing parameters and echocardiography indexes before and after pacemaker implantation were dynamically compared.

RESULTS

Pacing frequency and atrioventricular delay were adjusted to 60-70 beats per minute and 90-180 ms, respectively, in order to ensure the ratio of ventricular pacing was more than 98%. Pacing threshold and pacing impedance were kept in normal ranges. The differences of various pacing parameters were of no statistical significance within the 4 years of follow-up (P > 0.05). Compared with prior to pacing, it was observed that the IVS, VLVOT, and LVOTPG declined significantly (P < 0.01), the LVOTd widened significantly (P < 0.01), and the SAM phenomenon improved obviously (P < 0.01) at 1, 2, 3, and 4 years after pacemaker implantation. Additionally, the changes in LAD, LVEDd, LVPW, LVEF, and PASP were statistically insignificant (P > 0.05).

CONCLUSIONS

The cardiac structural reconstruction in patients with HOCM can be chronically improved by dual-chamber pacing therapy. The IVS, LVOTd, VLVOT, and LVOTPG can be used as sensitive and specific factors in evaluating the long-term effects of dual-chamber pacing therapy for HOCM.

Recent advances in genetics and treatment of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an intriguing disease with various clinical manifestations, ranging from sudden cardiac death to heart failure. The molecular genetics of HCM are all but elucidated and over 200 mutations in more than a dozen genes have been identified. Conventional therapeutic agents, namely beta-blockers and calcium channel blockers, could provide symptomatic relief but are not known to reduce mortality or induce regression of phenotype. Studies in genetic animal models suggest cardiac hypertrophy and fibrosis, a major histological feature of HCM, may be reversed or prevented through blockade of molecules involved in the pathogenesis of HCM. Surgical myomectomy and ethanol-induced septal ablation are effective procedures for reducing the left ventricular outflow tract obstruction and hence, symptomatic improvement. Randomized studies are needed to compare the effectiveness of medical therapy, ethanol septal ablation and surgical myomectomy in treatment of patients with HCM.

Pacing to treat low cardiac output syndrome following elective aortic valve replacement

We report a case of low cardiac output syndrome caused by dynamic left ventricular (LV) outflow obstruction after aortic valve replacement (AVR). This recognized phenomenon probably occurs more frequently than appreciated, and the author suggests that this should be considered when managing patients with severe hemodynamic instability after AVR. In addition, we also focus on the fact that invasive pacemaker systems have significant effects on cardiac output augmentation postoperatively and in long-term management of patients with LV outflow tract (LVOT) obstruction following AVR. The possible mechanisms and subsequent treatments are discussed.

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.

Pacing for drug-refractory or drug-intolerant hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a genetic disease with an autosomal-dominant inheritance for which negative inotropes are the most widely used initial therapies. Observational studies and small randomised trials have suggested symptomatic and functional benefits using pacing and several theories have been put forward to explain why. Pacing, although not the primary treatment for HCM, could be beneficial to patients with relative or absolute contraindications to surgery or alcohol ablation. Several randomised controlled trials comparing pacing to other therapeutic modalities have been conducted but no Cochrane-style systematic review has been done.

OBJECTIVES

To assess the effects of pacing in drug-refractory or drug-intolerant hypertrophic cardiomyopathy patients.

SEARCH METHODS

We searched the following on the 14/4/2010: CENTRAL (The Cochrane Library 2010, Issue 1), MEDLINE OVID (from 1950 onwards ), EMBASE OVID (from 1980 onwards ), Web of Science with Conference Proceedings (from 1970 onwards). No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials of either parallel or crossover design that assess the beneficial and harmful effects of pacing for hypertrophic cardiomyopathy were included. When crossover studies were identified, we considered data only from the first phase.

DATA COLLECTION AND ANALYSIS

Data from included studies were extracted onto a pre-formed data extraction paper by two authors independently. Data was then entered into Review Manager 5.1 for analysis. Risk of bias was assessed using the guidance provided in the Cochrane Handbook. For dichotomous data, relative risk was calculated; and for continuous data, the mean differences were calculated. Where appropriate data were available, meta-analysis was performed. Where meta-analysis was not possible, a narrative synthesis was written. A QUROUM flow chart was provided to show the flow of papers.

MAIN RESULTS

Five studies (reported in 10 papers) were identified. However, three of the five studies provided un-usable data. Thus the data from only two studies (reported in seven papers) with 105 participants were included for this review. There was insufficient data to compare results on all-cause mortality, cost effectiveness, exercise capacity, Quality of life and Peak O2 consumption.When comparing active pacing versus placebo pacing on exercise capacity, one study showed that exercise time decreased from (13.1 ± 4.4) minutes to (12.6 ± 4.3) minutes in the placebo group and increased from (12.1 ± 5.6) minutes to (12.9 ± 4.2) minutes in the treatment group (MD 0.30; 95% CI -1.54 to 2.14). Statistically significant data from the same study showed that left ventricular outflow tract obstruction decreased from (71 ± 32) mm Hg to (52 ± 34) mm Hg in the placebo group and from (70 ± 24) mm Hg to (33 ± 27) mm Hg in the active pacing group (MD -19.00; 95% CI -32.29 to -5.71). This study was also able to show that New York Heart Association (NYHA) functional class decreased from (2.5 ± 0.5) to (2.2 ± 0.6) in the inactive pacing group and decreased from (2.6 ± 0.5) to (1.7 ± 0.7) in the placebo group (MD -0.50; 95% CI -0.78 to -0.22).When comparing active pacing versus trancoronary ablation of septal hypertrophy (TASH), data from one study showed that NYHA functional class decreased from (3.2 ± 0.7) to (1.5 ± 0.5) in the TASH group and decreased from (3.0 ± 0.1) to (1.9 ± 0.6) in the pacemaker group. This study also showed that LV wall thickness remained unchanged in the active pacing group compared to reduction from (22 ± 4) mm to (17 ± 3) mm in the TASH group (MD 0.60; 95% CI -5.65 to 6.85) and that LV outflow tract obstruction decreased from (80 ± 35.5) mm Hg in the TASH group to (49.3 ± 37.7) mm Hg in the pacemaker group.

AUTHORS' CONCLUSIONS

Trials published to date lack information on clinically relevant end-points. Existing data is derived from small trials at high risk of bias, which concentrate on physiological measures. Their results are inconclusive. Further large and high quality trials with more appropriate outcomes are warranted.

Permanent pacing in patients with recurrence of symptoms and relapse of left ventricular obstruction at midcavity level after alcohol septal ablation

Treatment of symptom recurrence after initially successful alcohol septal ablation (ASA) in hypertrophic obstructive cardiomyopathy (HOCM) when accompanied by relapse of intracavitary left ventricular pressure gradient (LVG) is guided by the underlying mechanism. We describe our experience with permanent pacing in three patients with relapse of both LVG and symptoms 7 to 12 months after successful ASA. Even though pressure gradient recurrence was observed at midventricular level, we were able to achieve symptomatic improvement and LVG reduction after right ventricular apex pacing in all three cases. The effect on symptoms was long lasting-the 6-month followup echo-stress tests confirmed good exercise capacity and lack of provocable LVG. We found pacing to be a safe and effective treatment option in this clinical scenario. Based on our overall observations, we propose pacing as a niche treatment for patients with recurrence of LVG at midventricular level after ASA.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is a fascinating disease of marked heterogeneity. Hypertrophic cardiomyopathy was originally characterized by massive myocardial hypertrophy in the absence of known etiology, a dynamic left ventricular outflow obstruction, and increased risk of sudden death. It is now well accepted that multiple mutations in genes encoding for the cardiac sarcomere are responsible for the disease. Complex morphologic and pathophysiologic differences, disparate natural history studies, and novel treatment strategies underscore the challenge to the practicing cardiologist when faced with the management of the hypertrophic cardiomyopathy patient.

Interventional treatments for hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disorder. This autosomal dominant condition is defined by left ventricular hypertrophy and associated with functional limitation and premature death. In fact, many individuals are asymptomatic and the annual mortality in most modern series is 1% or less. However, severe symptoms may develop at any age, and the risk of premature death from arrhythmia, stroke, and progressive systolic impairment may complicate asymptomatic disease. The clinical management of patients with HCM therefore encompasses (1) genetic counseling including discussion of indications for genetic testing and cascade family screening, (2) assessment of prognostic risk from ventricular arrhythmia, stroke, and heart failure, and (3) symptom management. This article describes the interventional treatments in the management of severe symptoms associated with left ventricular outflow tract obstruction (LVOTO).

Effect of alcohol septal ablation in patients with hypertrophic cardiomyopathy on left-ventricular mechanical dyssynchrony as assessed by phase analysis of gated SPECT myocardial perfusion imaging

Patients with hypertrophic cardiomyopathy (HCM) may have delayed septal activation and left ventricular (LV) mechanical dyssynchrony, and may improve after alcohol septal ablation (ASA). This study used phase analysis of gated SPECT myocardial perfusion imaging (MPI) to evaluate septal activation and LV dyssynchrony in HCM patients pre- and post-ASA. Phase analysis was applied to 28 controls, and 32 HCM patients having rest MPI pre- and post-ASA to assess septal-lateral mechanical activation delay (SLD) and consequent LV dyssynchrony. In addition, phase analysis was applied to another group of 30 patients having serial MPI to measure variability of the LV dyssynchrony parameters on serial studies. ASA significantly reduced SLD and improved LV synchrony in the HCM patients with SLD < 0° due to earlier activation of the lateral wall relative to the septum. Based on the measured variability, 12 HCM patients had significant (Z < -1.65, P < 0.05) and 4 had moderate (Z < -1.00, P < 0.15) improvement in LV synchrony post-ASA. SLD < 0° predicted improvement in LV synchrony after ASA with a sensitivity of 81% and a specificity of 88%. SLD and LV dyssynchrony were frequent in HCM patients. HCM patients, whose septal activation became later than lateral activation, had significant reduction in septal activation delay and improvement in LV synchrony after ASA.

Hypertrophic cardiomyopathy in childhood

Hypertrophic cardiomyopathy has important differences in children compared with adults, particularly with regard to the range of causes and the outcomes in infants. Survival is highly dependent on etiology, particularly in the youngest patients, and pursuit of the specific cause is therefore necessary. The clinical utility of defining the genotype in children with familial hypertrophic cardiomyopathy exceeds that at other ages and has a highly favorable cost/benefit ratio. Although most of the available information concerning treatment and prevention of sudden death is derived in adults, management of children requires consideration of the differences in age-specific risk/benefit ratios.