Pacing for drug-refractory or drug-intolerant hypertrophic cardiomyopathy

Selective Interventricular Septal Radiofrequency Ablation in Patients With Hypertrophic Obstructive Cardiomyopathy: Who Can Benefit?

Introduction: Septal mass reduction is beneficial for hypertrophic obstructive cardiomyopathy (HOCM) patients with severe left ventricular outflow (LVOT) gradient and symptoms, with surgical myectomy or alcohol septal ablation (ASA) currently recommended in selected patients. Radiofrequency (RF) ablation of hypertrophied septum has been published as a novel method to alleviate LVOT obstruction in small populations. This study aims to investigate factors influencing clinical outcomes of radiofrequency septum ablation.

Methods and Results: In this study, 20 patients with HOCM who underwent endocardial ablation were included. Echocardiography and cardiac MRI (CMR) data was collected and analyzed pre- and (or) post- procedure. Nineteen patients underwent ablation successfully, while ablation was aborted in one patient with prior RBBB due to transient complete atrioventricular block (AVB). After 6 months of follow-up, NYHA heart functional class improved from III (2 - 3) to II (1 - 2) (p < 0.001), and resting LVOT gradient was significantly reduced (87.6 ± 29.5 mmHg vs. 48.1 ± 29.7, p < 0.001). LVOT gradient reduction was significantly higher in patients with limited basal septal hypertrophy (60.9 ± 8.3 vs. 27.9 ± 7.1, p = 0.01), shorter anterior mitral leaflet (56.1 ± 6.4 vs. 20.4 ± 5.0, p < 0.01), and normally positioned papillary muscle (36.9 ± 7.1 vs. 75.0 ± 6.3, p < 0.05).

Conclusions: Endocardial septal ablation appears to be a safe and effective procedure for alleviating LVOT gradient in patients with HOCM, especially in those with limited basal septal hypertrophy, shorter anterior mitral leaflet, and normal positioned papillary muscle.

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.

Molecular autopsy and family screening in a young case of sudden cardiac death reveals an unusually severe case of FHL1 related hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a genetic cardiomyopathy with a prevalence of about 1:200. It is characterized by left ventricular hypertrophy, diastolic dysfunction and interstitial fibrosis; HCM might lead to sudden cardiac death (SCD) especially in the young. Due to low autopsy frequencies of sudden unexplained deaths (SUD) the true prevalence of SCD and especially of HCM among SUD remains unclear. Even in cases of proven SCD genetic testing is not a routine procedure precluding appropriate risk stratification and counseling of relatives.

METHODS

Here we report a case of SCD in a 19-year-old investigated by combined forensic and molecular autopsy.

RESULTS

During autopsy of the index-patient HCM was detected. As no other possible cause of death could be uncovered by forensic autopsy the event was classified as SCD. Molecular autopsy identified two (probably) pathogenic genetic variants in FHL1 and MYBPC3. The MYBPC3 variant had an incomplete penetrance. The FHL1 variant was a de novo mutation. We detected reduced FHL1 mRNA levels and no FHL1 protein in muscle samples suggesting nonsense-mediated mRNA decay and/or degradation of the truncated protein in the SCD victim revealing a plausible disease mechanism.

CONCLUSION

The identification of the genetic cause of the SCD contributed to the rational counseling of the relatives and risk assessment within the family. Furthermore our study revealed evidences for the pathomechanism of FHL1 mutations.

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.

Disclosure of diagnosis to at-risk relatives by individuals diagnosed with hypertrophic cardiomyopathy (HCM)

Hypertrophic cardiomyopathy (HCM) affects 1 in 200 people and is the most common cause of sudden cardiac death in the young. Given that HCM usually is inherited in an autosomal dominant pattern, an HCM diagnosis has implications for biologically related family members. The purpose of this study was to explore probands' disclosure of an HCM diagnosis with these biologically related, at-risk family members. An online survey was posted on the website of the Hypertrophic Cardiomyopathy Association (HCMA), an advocacy and support group for HCM patients and their families. Descriptive statistics were used to summarize responses to closed-ended questions and demographics. Using an iterative content analysis with the constant comparison approach, we analyzed the responses to open-ended questions inquiring about the nature and role of disclosure communication with at-risk relatives. A total of 315 individuals with a self-reported diagnosis of HCM completed the survey. Most participants (98%) disclosed their diagnosis to at-risk family members. Sixty-four percent disclosed to family members less than 1 year after diagnosis. Participants also disclosed potential treatment options (74.6%) and the emotional impact of the diagnosis (39%). HCM specialists were ranked by participants as being the most helping in explaining the benefit of genetic counseling, while genetic counselor were ranked as least helpful. Emerging themes address the need to encourage screening and genetic testing among family members and to identify external educational resources for use during the disclosure process. Importantly, our study found that the process of disclosure varies based on individuals' experiences and family communication dynamics. However, almost all participants expressed the importance of disclosing the diagnosis of HCM as well as the importance of being screened and expressed needs for additional support during the disclosure process.

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.

Hypertrophic obstructive cardiomyopathy-the Leipzig experience

BACKGROUND

Management of hypertrophic obstructive cardiomyopathy (HOCM) has evolved considerably over the last fifty years, and includes medical treatment as well as septal myectomy (SM) to relief symptoms caused by left ventricular outflow tract obstruction (LVOTO). We report the Leipzig Heart Center experience in the surgical management of patients with HOCM.

METHODS

We collected data from all patient treated surgically with a myectomy for LVOTO in patients with HOCM between 1997 and 2016. Patients with absent data were excluded from our analysis. All data were obtained from our surgical database and analyzed retrospectively.

RESULTS

We identified 115 patients who underwent surgical treatment for HOCM, where a male:female ratio of 1.1:1, a mean age of 60.8±14.6 years and a body mass index of 27.7±4.5 were observed. The most common symptom was dyspnea (n=102). Of all patients, 50% had New York Heart Association (NYHA) III class symptoms. Arterial hypertension was the most common comorbidity (n=80). Preoperative transthoracic echocardiography showed a mean ejection fraction (EF) of 65.9%±9.7%, median septal thickness of 21.1±5.3 mm, systolic anterior motion of the mitral valve (MV) in 61.7% of patients, and mean LVOT gradient of 70.1±45.2 mmHg. Surgery resulted in a mean decrease of the septal thickness by 15±3.7 mm and LVOT gradient by 9.7±8.5 mmHg. Isolated SM was carried out on 20 patients. Postoperatively, we were able to notice a significant improvement in NYHA classification, in which patients with NYHA III benefitted most from SM. Long-term follow-up data up to 11.3±0.7 years were available for 114 patients. During follow-up, 16 patients died, and one patient was lost to follow up.

CONCLUSIONS

Surgical treatment of LVOT in patients with HOCM is an effective intervention that improves cardiac function and quality of life (QoL) and is associated with a low operative risk.

[Primary and secondary prophylactic ICD therapy in congenital electrical and structural cardiomyopathies]

Congenital electrical and structural cardiomyopathies are rare and associated with an increased risk for syncope and sudden cardiac death in the young. Due to the young age of the patients and the limited data available, risk stratification and especially ICD therapy are challenging. In this young patient collective, ICD therapy is associated with a high complication rate, which does not justify unreserved primary prophylactic ICD implantation. The aim of this review is to elucidate risk stratification and ICD therapy of various electrical and structural cardiomyopathies.

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.

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.

Alcohol Septal Ablation for the Treatment of Hypertrophic Obstructive Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an inherited myocardial disorder characterised by left ventricular hypertrophy. A subgroup of patients develops limiting symptoms in association with left ventricular outflow tract obstruction (LVOTO). Current international guidelines recommend that symptomatic patients are initially treated by alleviating exacerbating factors and negatively inotropic medication. Drug-refractory symptoms require a comprehensive evaluation of the mechanism of LVOTO and review by a multidisciplinary team to consider the relative merits of myectomy, alcohol septal ablation (ASA) and pacing. This article provides a brief overview of HCM and the pathophysiology of LVOTO, and reviews the use of ASA in patients with drug-refractory symptoms secondary to LVOTO.