Appraisal of dual-chamber pacing therapy in hypertrophic cardiomyopathy: too soon for a rush to judgment?

Transcatheter septal ablation in hypertrophic obstructive cardiomyopathy: a technical guide and review of published results

Transcatheter alcohol septal ablation (ASA) treatment of symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM) is based on the existence and degree of intraventricular obstruction. Patients with significant gradient and symptoms who do not respond to optimal medical therapy are eligible to gradient reduction through a surgical (septal myectomy) or a transcatheter (alcohol septal ablation) septal reduction. The latter encompasses occlusion of a septal branch perfusing the hypertrophied septum, which is involved in the generation of obstruction, by injecting ethanol into the supplying septal branch(es). ASA has been established as a highly effective and safe method and has outnumbered the surgical gold standard. Although the technique is straightforward, patient selection and some technical details may influence the efficacy and safety of the procedure. The technique is based on echocardiographic contrast guidance, which allows accurate target septal branch selection and optimisation of the result. Published long-term results from high-volume centres have confirmed the effectiveness of ASA and have shown excellent survival, which is comparable to that in the general population. Choice and performance of the surgical or interventional treatment should be implemented in highly specialised centres in terms of a heart-team approach, taking notice of anatomic characteristics as well as comorbidities. Involvement of all cases in international registries may reveal the individual merits and indications for the surgical and interventional treatment in HOCM.

Twenty Years of Alcohol Septal Ablation in Hypertrophic Obstructive Cardiomyopathy

Hypertrophic obstructive cardiomyopathy is the most common genetic cardiac disease and is generally characterised by asymmetric septal hypertrophy and intraventricular obstruction. Patients with severe obstruction and significant symptoms that persist despite optimal medical treatment are candidates for an invasive septal reduction therapy. Twenty years after its introduction, percutaneous transluminal alcohol septal ablation has been increasingly preferred for septal reduction in patients with drug refractory hypertrophic obstructive cardiomyopathy. Myocardial contrast echocardiography and injection of reduced alcohol volumes have increased safety, while efficacy is comparable to the surgical alternative, septal myectomy, which has for decades been regarded as the 'gold standard' treatment. Data on medium- and long-term survival show improved prognosis with survival being similar to the general population. Current guidelines have supported its use by experienced operators in centres specialised in the treatment of patients with hypertrophic obstructive cardiomyopathy.

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.

Percutaneous myocardial ablation for left mid-ventricular obstructive hypertrophic cardiomyopathy

Mid-ventricular obstructive hypertrophic cardiomyopathy (MVOHC) is a rare type of cardiomyopathy. The diagnosis is based on the hourglass appearance on the left ventriculogram and the presence of pressure gradient between apical and basal chamber of the ventriculum on the hemodynamic assessment. Atrio-ventricular sequential pacing and alcohol ablation have been proposed as less invasive alternatives to surgery for patients who fail to respond to pharmacologic therapy. The present case represents successful percutaneous treatment with alcohol ablation to patient with MVOHC and apical aneurysm. Alcohol ablation to distal segment of the left anterior descending artery resulted with relief of clinical symptoms and intra-ventricular pressure gradient.

Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy

HOCM is a rare disorder of myocardium that may result in asymmetrical left ventricular septal hypertrophy and dynamic outflow obstruction. This may result in hemodynamic sequel that leads to deterioration of functional class in the majority of patients. Alcohol septal ablation may provide symptomatic relief in the majority of patients who fail medical therapy or who experience significantly high outflow gradients.

Remodelado ventricular izquierdo tras ablación septal percutánea con alcohol en pacientes con miocardiopatía hipertrófica obstructiva: estudio ecocardiográfico

INTRODUCTION

In patients with hypertrophic obstructive cardiomyopathy, obstruction in the left ventricular outflow tract may generate more hypertrophy. Our aim was to evaluate the impact of reducing ventricular outflow tract obstruction on left ventricular hypertrophy and remodeling after alcohol septal ablation.

PATIENTS AND METHOD

20 patients with hypertrophic obstructive cardiomyopathy who underwent alcohol septal ablation were included. Doppler echocardiography was performed in all patients at baseline, immediately after alcohol septal ablation, and at 3 and 12 months' follow-up. Left ventricular diameters and wall thickness and pressure gradients in the ventricular outflow tract were determined.

RESULTS

Immediately after alcohol septal ablation, ventricular outflow tract pressure gradient decreased from 63.0 27.7 to 28.2 24.7 mmHg (p < 0.001), without significant changes in left ventricular dimensions. However, after 12 months we observed an increase in left ventricular end-diastolic (from 47.1 4.9 to 50.8 4.5 mm) and end-systolic diameter (from 27.1 3.0 to 33.7 4.6 mm), as well as a reduction in septal (from 19.5 4.0 to 15.5 2.7 mm) and posterior wall thickness (from 14.0 2.2 to 12.9 1.3 mm) (p < 0.01 in all cases). Left ventricular end-diastolic and end-systolic volumes increased (from 106.4 26.9 to 123.1 28.7 ml and from 50.2 17.3 to 56.7 18.3 ml, respectively, p < 0.01 in both cases), without changes in left ventricular ejection fraction. The reduction in ventricular outflow tract pressure gradient at 12 months' follow-up correlated significantly with the increase in left ventricular end-systolic diameter (r = 0.63; p < 0.01).

CONCLUSIONS

In patients with hypertrophic obstructive cardiomyopathy who underwent alcohol septal ablation, relief of ventricular outflow tract obstruction is associated with an increase in left ventricular chamber diameters and volume. These findings suggest that middle- and long-term ventricular remodeling and regression of hypertrophy occur in these patients, which may contribute to their clinical improvement.

[Therapeutic approaches in symptomatic hypertrophic obstructive cardiomyopathy]

Hypertrophic cardiomyopathy is a complex and heterogeneous disease. Although most patients experience just a few symptoms, and have a good prognosis, there are others whose symptoms are severe and progressive, determined by different pathophysiological elements such as diastolic dysfunction, myocardial ischemia, arrhythmias and subaortic obstruction. Approximately 20-30% of hypertrophic cardiomyopathy patients develop an intraventricular dynamic gradient, which in some cases, is responsible for severe symptoms which are ameliorated once the obstruction is reduced. In many cases the symptoms can be controlled with medical treatment which includes betablockers, calcium-channel antagonists and dysopiramide, but some patients will still experience severe and refractory symptoms. This subgroup of patients, which represent approximately 5-10% of patients with hypertrophic cardiomyopathy, can be problematic from a management perspective. For many years, septal myectomy and/or mitral valve replacement offered the only effective alternative therapy for these patients. However, the high rates of morbidity and mortality associated with these procedures have necessitated the search for new and less invasive procedures such as ventricular pacing and percutaneous septal ablation. Although the initial results with sequential pacing were encouraging, further studies have suggested a significant placebo effect, which makes its application controversial. In the last 5 years selective embolization of the septal artery precipitating a localized myocardial infarction has been utilized to reduce the subaortic gradient. The potential indications and efficacy of these new forms of treatment, like ventricular pacing and percutaneous septal ablation, are presently under evaluation and are the main subject of this review. Medical treatment, with either beta-blockers, calcium channel antagonists or dysopiramide constitutes the first therapeutic step. Surgery, while alleviating the subaortic obstruction and reducing the intraventicular pressure and mitral insufficiency, produces important and long-lasting symptomatic and functional improvement in most of these patients, and it continues to be an important therapeutic alternative in these cases. If the first results with sequential pacemaker implants were encouraging, today it is alluded to an important placebo effect that causes its application to be controversial. In the last 5 years the path has been made in the creation of a septal infarction located through the embolization of the septal branches to reduce the gradient.

Current status of alcohol septal ablation for patients with hypertrophic cardiomyopathy

Since the early 1960s, surgical myotomy-myectomy has been the standard treatment for patients with drug-refractory symptoms due to hypertrophic cardiomyopathy and dynamic outflow tract obstruction. Comparable morphologic and functional results can be achieved by percutaneous septal ablation (PTSMA) by alcohol-induced septal branch occlusion. The circumscribed therapeutic myocardial infarction results in widening of the left ventricular outflow tract with consecutive gradient reduction. Follow-up studies show clinical and objective improvement as well as further gradient reduction due to left ventricular remodeling. In this article, an updated review of the latest results of PTSMA is provided.

Pacing in hypertrophic cardiomyopathy

Dual chamber pacing has been proposed as an alternative to surgery in the management of hypertrophic cardiomyopathy. Reports have documented hemodynamic and symptomatic benefit from dual chamber pacing, raising the question of whether or not all patients with drug-refractory symptoms should undergo a trial of pacing before consideration of surgery. The enthusiasm for pacing in hypertrophic cardiomyopathy has generated a number of investigations addressing this issue, including several recently concluded clinical trials. This article reviews the recent experience with dual chamber pacing in hypertrophic cardiomyopathy.

Medical therapy versus interventional therapy in hypertropic obstructive cardiomyopathy

Medical treatment in symptomatic patients with hypertrophic obstructive cardiomyopathy aims to reduce the outflow tract gradients, and to improve diastolic dysfunction and rhythm disorders. Surgical myectomy is the standard treatment in patients with drug refractory symptoms. Since the early 1990s, dual-chamber (DDD)-pacemaker implantation and percutaneous transluminal septal myocardial ablation by alcohol-induced septal branch occlusion have widened treatment options in this subgroup of patients. An overview of medical and interventional treatment is presented.

Assessment of permanent dual-chamber pacing as a treatment for drug-refractory symptomatic patients with obstructive hypertrophic cardiomyopathy. A randomized, double-blind, crossover study (M-PATHY)

BACKGROUND

Dual-chamber pacing (DDD) has been proposed as a treatment alternative to surgery for severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM), based largely on uncontrolled studies.

METHODS AND RESULTS

This prospective, multicenter trial assessed pacing in 48 symptomatic HCM patients with >/=50 mm Hg basal gradient, refractory to drug therapy. Patients were randomized to 3 months each of DDD pacing and pacing backup (AAI-30) in a double-blind, crossover study design, followed by an uncontrolled and unblinded 6-month pacing trial. With randomization, no significant differences were evident between pacing and no pacing for subjective or objective measures of symptoms or exercise capacity, including NYHA functional class, quality of life score, treadmill exercise time or peak oxygen consumption. After 6 additional months of unblinded pacing, functional class and quality of life score were improved compared with baseline (P<0.01), but peak oxygen consumption was unchanged. Outflow gradient decreased 40%, 82+/-32 mm Hg to 48+/-32 mm Hg (P<0. 001), and was reduced in 57% of patients but showed no change or an increase in 43%. At 12 months, 6 individual patients (12%) showed improved functional capacity; each was 65 to 75 years of age. Left ventricular wall thicknesses in the overall study group showed no remodeling between baseline (22+/-5 mm) and 12 months (21+/-5 mm; P=NS).

CONCLUSIONS

(1) Pacing cannot be regarded as a primary treatment for obstructive HCM; (2) with randomization, perceived symptomatic improvement was most consistent with a substantial placebo effect; (3) longer, uncontrolled pacing periods were associated with some subjective benefit but unaccompanied by objective improvement in cardiovascular performance and should be interpreted cautiously; (4) modest reduction in outflow gradient was achieved in most patients; and (5) a small subset (12%) >/= 65 years of age showed a clinical response, suggesting that DDD pacing could be a therapeutic option for some elderly patients.

[Clinical picture and therapy of hypertrophic cardiomyopathy]

Hypertrophic cardiomyopathy is defined as a primary, sometimes familial and genetically fixed myocardial hypertrophy. In the obstructive form of the disease (HOCM) a dynamic outflow tract obstruction of the left, occasionally also the right ventricle can be found. HOCM is the most frequent cause of stress-induced syncope or sudden cardiac death in younger patients. An individual estimation of prognosis is difficult although several risk factors have been identified. In addition to standard therapy of symptomatic patients (medical treatment with betablockers and calcium-antagonists of verapamil-type as well as surgical myotomy/myectomy) DDD-pacemaker implantation and percutaneous transluminal septal myocardial ablation (PTSMA) by alcohol-induced septal branch occlusion have been introduced. After PTSMA significant outflow tract gradient reduction can be achieved in > 90% of patients. Due to remodeling after circumscribed myocardial necrosis further gradient reduction has been observed during follow-up. Optimization of ablated septal area by echocardiographic monitoring resulted in reduction of the most important complication (trifascicular block with need of permanent pacemaker implantation) and improvement of acute and follow-up results. Long-term follow-up and comparison with established treatment options are necessary to evaluate the definitive importance of the promising new treatment.

Percutaneous transluminal septal myocardial ablation in hypertrophic obstructive cardiomyopathy: acute results and 3-month follow-up in 25 patients

OBJECTIVES

We report the acute results and midterm clinical course after percutaneous transluminal septal myocardial ablation (PTSMA) in symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM).

BACKGROUND

In the treatment of HOCM, surgical myectomy and DDD pacemaker therapy are considered the standard procedural extensions to drug therapy with negatively inotropic drugs. As an alternative nonsurgical procedure for reducing the left ventricular outflow tract (LVOT) gradient, PTSMA by alcohol-induced septal branch occlusion was introduced. However, clinical follow-up has not been sufficiently described.

METHODS

In 25 patients (13 women, 12 men; mean [+/- SD] age 54.7 +/- 15.0 years) who were symptomatic despite sufficient drug therapy, 1.4 +/- 0.6 septal branches were occluded with an injection of 4.1 +/- 2.6 ml of alcohol (96%) to ablate the hypertrophied interventricular septum. After 3-months, follow-up results of LVOT gradients and clinical course were determined.

RESULTS

The invasively determined LVOT gradients could be reduced in 22 patients (88%), with a mean reduction from 61.8 +/- 29.8 mm Hg (range 4 to 152) to 19.4 +/- 20.8 mm Hg (range 0 to 74) at rest (p < 0.0001) and from 141.4 +/- 45.3 mm Hg (range 76 to 240) to 61.1 +/- 40.1 mm Hg (range 0 to 135) after extrasystole. All patients had angina pectoris for 24 h. The maximal creatine kinase increase was 780 +/- 436 U/liter (range 305 to 1,810) after 11.1 +/- 6.0 h (range 4 to 24). Thirteen patients (52%) developed a trifascicular block for 5 min to 8 days requiring temporary (n = 8 [32%]) or permanent (DDD) pacemaker implantation (n = 5 [20%]). An 86-year old woman died 8 days after successful intervention of uncontrollable ventricular fibrillation in conjunction with beta-sympathomimetics in chronically obstructive pulmonary disease. The remaining patients were discharged after 11.3 +/- 5.4 days (range 5 to 24), after an uncomplicated hospital course. Clinical and echocardiographic follow-up was achieved in all 24 surviving patients after 3 months. No cardiac complications occurred. Twenty-one patients (88%) showed clinical improvement, with a New York Heart Association functional class of 1.4 +/- 1.1. A further reduction in LVOT gradient was shown in 14 patients (58%).

CONCLUSIONS

PTSMA of HOCM is a promising nonsurgical technique for septal myocardial reduction, with a consecutive reduction in LVOT gradient. Possible complications are trifascicular blocks, requiring permanent pacemaker implantation, and tachycardiac rhythm disturbances. Clinical long-term observations of larger patient series and a comparison with conventional forms of therapy are necessary to determine the conclusive therapeutic significance.

The importance of atrial contribution: a case study of dual-chamber pacing in hypertrophic obstructive cardiomyopathy

Beta blockers and calcium channel blockers are the mainstay of therapy for hypertrophic obstructive cardiomyopathy. Recent evidence suggests that dual-chamber pacing may also relieve symptoms in a subset of patients. Proper interval programming is critical to the success of this intervention-as well as maintenance of the atrial contribution to preserve left ventricular diastolic filling. This report illustrates the importance of atrial contribution, as well as the loss of atrial capture, which can lead to hemodynamic deterioration and recurrence of symptoms.

Effects of dual-chamber pacing for pediatric patients with hypertrophic obstructive cardiomyopathy

OBJECTIVES

The effects of both temporary and permanent dual-chamber pacing (DCP) were evaluated in symptomatic pediatric patients with hypertrophic obstructive cardiomyopathy (HOCM) unresponsive to medications.

BACKGROUND

Permanent DCP pacing can reduce left ventricular outflow tract (LVOT) gradient and relieve symptoms in adult patients with HOCM.

METHODS

Ten patients (mean [+/-SD] age 11.1 +/- 6 years, range 1 to 17.5) with HOCM and a Doppler LVOT gradient > or = 40 mm Hg were studied. The seven patients showing hemodynamic improvement during temporary pacing at cardiac catheterization underwent surgical implantation of a permanent DCP system. The effects of permanent pacing were evaluated using a questionnaire, Doppler evaluation, treadmill testing and repeat cardiac catheterization.

RESULTS

At initial cardiac catheterization, three patients failed to respond to temporary pacing (inadequate pace capture in two; congenital mitral valve abnormality in one). The remaining seven patients (70%, 95% confidence interval 38.0% to 91.7%, mean age 13 +/- years, range 4 to 17.5) showed a significant reduction (p < 0.05) in LVOT gradient, left ventricular systolic pressure and pulmonary capillary wedge pressure. After pacemaker implantation, these seven patients reported a significant reduction in dyspnea on exertion and exercise intolerance. Serial Doppler evaluation showed a significant reduction in LVOT gradient. Follow-up catheterization at 23 +/- 4 months in six patients (one patient declined restudy) showed a persistent decrease in LVOT gradient (53 +/- 13 vs. 16 +/- 11 mm Hg), left ventricular systolic pressure (149 +/- 16 vs. 108 +/- 14 mm Hg) and pulmonary capillary wedge pressure (18 +/- 2 vs. 12 +/- 4 mm Hg) versus preimplantation values.

CONCLUSIONS

Permanent DCP is an effective therapy for selected pediatric patients with HOCM. Rapid atrial rates and intrinsic atrioventricular conduction, as well as congenital mitral valve abnormalities, may preclude effective pacing in certain patients.