Improvement in exercise capacity and exercise blood pressure response after transcoronary alcohol ablation therapy of septal hypertrophy in hypertrophic cardiomyopathy

Current therapies for hypertrophic cardiomyopathy: a systematic review and meta-analysis of the literature

AIMS

The aim of this study was to synthesize the evidence on the effect of the current therapies over the pathophysiological and clinical characteristics of patients with hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

A systematic review and meta-analysis of 41 studies identified from 1383 retrieved from PubMed, Web of Science, and Cochrane was conducted. Therapies were grouped in pharmacological, invasive and physical exercise. Pharmacological agents had no effect on functional capacity measured by VO2max (1.11 mL/kg/min; 95% CI: -0.04, 2.25, P < 0.05). Invasive septal reduction therapies increased VO2max (+3.2 mL/kg/min; 95% CI: 1.78, 4.60, P < 0.05). Structured physical exercise programmes did not report contraindications and evidenced the highest increases on functional capacity (VO2max + 4.33 mL/kg/min; 95% CI: 0.20, 8.45, P < 0.05). Patients with left ventricular outflow tract (LVOT) obstruction at rest improved their VO2max to a greater extent compared with those without resting LVOT obstruction (2.82 mL/kg/min; 95% CI: 1.97, 3.67 vs. 1.18; 95% CI: 0.62, 1.74, P < 0.05). Peak LVOT gradient was reduced with the three treatment options with the highest reduction observed for invasive therapies. Left ventricular ejection fraction was reduced in pharmacological and invasive procedures. No effect was observed after physical exercise. Symptomatic status improved with the three options and to a greater extent with invasive procedures.

CONCLUSIONS

Invasive septal reduction therapies increase VO2max, improve symptomatic status, and reduce resting and peak LVOT gradient, thus might be considered in obstructive patients. Physical exercise emerges as a coadjuvant therapy, which is safe and associated with benefits on functional capacity. Pharmacological agents improve reported NYHA class, but not functional capacity.

Prognostic Significance of Initial r-Wave in Leads V1 and aVR Before PTSMA in Patients with Hypertrophic Obstructive Cardiomyopathy

Objective

Percutaneous transluminal septal myocardial ablation (PTSMA) is one of the septal reduction therapies without all satisfactory results in hypertrophic obstructive cardiomyopathy (HOCM) patients. Initial r-wave in leads V1 and aVR on the surface electrocardiography is the sign of ventricular septal base depolarization. Whether the initial r-wave in leads V1 and aVR is predictive of good mid-term response to PTSMA in patients with HOCM remains unknown.

Design, Settings, and Participants

Among 546 consecutive patients evaluated in Fuwai Hospital (Beijing, China), we selected HOCM patients who underwent PTSMA. During the 3-year follow-up after PTSMA, primary outcomes included death, surgical myectomy, syncope, and NYHA classification III/IV.

Results

At last, 85 patients were selected, and were assigned to 3 groups based on the presence of initial r-wave in leads V1 and aVR. Through multivariable Cox and Kaplan–Meier method, patients with initial r-wave in both leads V1 and aVR were independently associated with a decreased risk of primary outcomes (HR: 0.112; 95% CI: 0.024 to 0.518; p = 0.005) during 3-years’ follow-up.

Conclusion

The results suggest that the presence of initial r-wave in both leads V1 and aVR on the surface 12-lead ECG is highly predictive of good mid-term response to PTSMA in patients with HOCM.

Incidence of Atrial Fibrillation following Alcohol Septal Ablation for Hypertrophic Cardiomyopathy

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) are at a fourfold to sixfold higher risk of developing atrial fibrillation (AF) compared to the general population, though incidence rates among patients undergoing alcohol septal ablation (ASA) are not well characterized. The purpose of this study was to evaluate atrial fibrillation incidence following ASA.

METHODS

We studied 132 consecutive HCM patients without comorbid AF that underwent 154 ASA procedures. The incidence of AF in follow-up was assessed through chart abstraction including electrocardiography. Survival free of AF was estimated using Kaplan-Meier methodology.

RESULTS

Over a mean follow-up of 3.6 ± 2.7 years (maximum 11.3 years), 10 (7.6%) patients developed new-onset AF. Of those who developed AF, both resting and provoked left ventricular outflow tract (LVOT) gradients had improved significantly (difference -79.78 mm Hg, P ≤ 0.005). Severity of mitral regurgitation improved in 7 (70%) patients. Survival free of AF was estimated to be 99.1%, 93.7%, and 91.7% at 1, 3, and 5 years.

CONCLUSIONS

Despite relieving LVOT obstruction and improving mitral regurgitation severity via ASA, new-onset AF remained a common complication of hypertrophic cardiomyopathy.

Percutaneous transluminal radiofrequency closure of the coronary artery in animal studies

The aim of this study was to investigate the safety and effectiveness of a novel method for the selective transcoronary closure of small coronary arteries by the intraluminal application of radiofrequency (RF) energy. Twenty-six small (diameter of 1–2 mm) coronary artery branches were selected in 13 dogs. An RF electrode wire (CRW-Zcy) was placed into the target vessel and a coronary balloon was used to transiently block the blood flow and limit damage to the proximal vessel. A therapeutic dosage of 20–30 W of RT energy every 10–30 sec (selected according the diameter of the target artery) was discharged via the CRW-Zcy inside a microcatheter two or three times in order to achieve arterial closure. A high dosage of 60 W every 120 sec of RF energy was used to conduct the safety study. All 26 branches were successfully closed resulting in the complete blockage of the antegrade and retrograde flows. The area of injury was limited to the target artery and the supplied myocardium. High-dose RF did not cause injury to the adjacent vessels and myocardium. The animals tolerated the procedure well without any untoward systemic effects. A follow-up angiography at two weeks revealed no evidence of recanalization or retrograde filling of the target artery. Percutaneous transluminal radiofrequency closure is a safe and effective interventional approach for closing the small coronary arteries, and is potentially valuable for further investigation.

Long-term outcome of percutaneous transluminal septal myocardial ablation in hypertrophic obstructive cardiomyopathy: a Scandinavian multicenter study

BACKGROUND

Single-center reports on percutaneous transluminal septal myocardial ablation (PTSMA) in patients with hypertrophic obstructive cardiomyopathy have shown considerable differences in outcome.

METHODS AND RESULTS

We report the long-term outcome of 313 PTSMA procedures performed in 279 patients with hypertrophic obstructive cardiomyopathy aged 59±14 years from 1999 to 2010 in 4 Scandinavian centers. Sixty-nine percent of patients had ≥1 comorbidity at baseline. The median (interquartile range) of left ventricular outflow tract gradient at rest was reduced from 58 mm Hg (34 to 89 mm Hg) at baseline to 12 mm Hg (8 to 24 mm Hg) at 1-year (P<0.001) and during Valsalva maneuver from 93 mm Hg (70 to 140 mm Hg) to 21 mm Hg (11 to 42 mm Hg) (P<0.001). The proportion of patients with syncope was reduced from 18% to 2% (P<0.001), and the proportion in New York Heart Association class III/IV was reduced from 94% to 21% (P<0.001). All treatment effects remained stable during the follow-up. New York Heart Association class III/IV at the most recent follow-up (2.9±2.6 years) was associated with diabetes mellitus (P=0.03), chronic obstructive pulmonary disease (P=0.02), and valve disease unrelated to hypertrophic cardiomyopathy (P<0.01). In-hospital mortality was 0.3%. The 1-, 5- and 10-year survival rates were 97%, 87%, and 67%, respectively (P=0.06 versus an age- and sex-matched background population) in all patients and 99%, 94%, and 88%, respectively (P=0.12) in patients aged <60 years (48±9 years, n=141). Age (hazard ratio, 1.07; 95% CI, 1.03 to 1.1) was the only predictor of survival.

CONCLUSIONS

In this multicenter study, the in-hospital mortality after PTSMA was low despite considerable comorbidities. The hemodynamic and symptomatic effects were sustained long term. The long-term symptomatic outcome was associated with baseline comorbidities. The 10-year survival rate was comparable to that in an age- and sex-matched background population, and age was the only predictor of survival.

Controversies in cardiovascular medicine. Hypertrophic obstructive cardiomyopathy: alcohol septal ablation

Alcohol septal ablation (ASA) was introduced in 1994 as an alternative to septal myectomy for patients with hypertrophic obstructive cardiomyopathy and symptoms refractory to medical therapy. This procedure alleviates symptoms by producing a targeted, limited infarction of the upper interventricular septum, resulting in an increase in left ventricular outflow tract (LVOT) diameter, a decrease in LVOT gradient, and regression of the component of LV hypertrophy that is due to pressure overload. Clinical success, with improvement in symptoms and reduction in gradient, is achieved in the great majority of patients with either resting or provocable LVOT obstruction. The principal morbidity of the procedure is complete heart block, resulting in some patients in the requirement for a permanent pacemaker. The introduction of myocardial contrast echocardiography as a component of the ASA procedure has contributed to the induction of smaller myocardial infarctions with lower dosages of alcohol and, in turn, fewer complications. Non-randomized comparisons of septal ablation and septal myectomy have shown similar mortality rates and post-procedure New York Heart Association class for the two procedures.

Resolution of left ventricular and asymmetric septal hypertrophy after resection of left ventricular outflow obstruction in a patient with troponin-positive hypertrophic obstructive cardiomyopathy: a case report

We report the case of a young woman with a troponin mutation of C to T nucleotide substitution in exon 17 of troponin 2 (TNNT2; c.868C.T; p.Arg288Cys) leading to hypertrophic obstructive cardiomyopathy. Following surgical resection of the outflow obstruction, she had near-complete resolution of her asymmetric left ventricular hypertrophy, such that cardiomyopathy could no longer be diagnosed on echocardiographic grounds. We believe that this unusual case shows important aspects relating to the interplay between genetic and environmental mechanisms and the overlap in the phenotypic spectrum between primary subaortic stenosis and obstructive hypertrophic cardiomyopathy.

Meta-Analyses of Septal Reduction Therapies for Obstructive Hypertrophic Cardiomyopathy

Background— Septal reduction for obstructive hypertrophic cardiomyopathy may be performed by surgical myectomy or alcohol septal ablation (ASA). Unlike surgical myectomy, ASA creates an intramyocardial scar that may potentiate the risk of ventricular arrhythmias and sudden cardiac death (SCD).

Methods and Results— Systematic reviews for ASA and surgical myectomy were performed. Study selection and data extraction were completed independently by 2 investigators. Comparative data analyses were completed using a random effects model and regression analysis. Kappa statistics for agreement on initial study inclusion were high for both ASA (0.78; 95% CI, 0.68 to 0.88) and surgical myectomy studies (0.95; 95% CI, 0.84 to 1.0). Nineteen ASA studies (2207 patients) and 8 surgical myectomy studies (1887 patients) were included. Median follow-up was shorter for ASA than for myectomy studies (51 versus 1266 patient-years; P <0.001). For ASA and surgical myectomy, unadjusted rates (events/patient-years) of all-cause mortality (0.021 versus 0.018, respectively; P =0.37) and SCD (0.004 versus 0.003, respectively; P =0.36) were similar. Patients treated with ASA were older (weighted mean, 55 versus 44 years; P <0.001) and had less septal hypertrophy (weighted mean, 21 versus 23 mm; P <0.001) compared with those treated with myectomy. After adjustment for available baseline characteristics, odds ratios for treatment effect on all-cause mortality and SCD were 0.28 (95% CI, 0.16 to 0.46) and 0.32 (95% CI, 0.11 to 0.97), respectively, favoring ASA.

Conclusions— Rates of all-cause mortality and SCD after both ASA and surgical myectomy were similarly low. Adjusted for baseline characteristics, the odds ratios for treatment effect on all-cause mortality and SCD were lower in ASA cohorts compared with surgical myectomy cohorts.

Abnormal blood-pressure response to exercise and oxygen consumption in patients with hypertrophic cardiomyopathy

BACKGROUND

Abnormal blood-pressure response during exercise occurs in about one third of patients with hypertrophic cardiomyopathy (HCM), and it has been associated with a high risk of sudden cardiac death. We assessed the hemodynamics of exercise in HCM patients with abnormal blood-pressure response by using ambulatory radionuclide monitoring (VEST) of left-ventricular (LV) function, and exercise tolerance by oxygen consumption.

METHODS

Twenty-two HCM patients underwent treadmill exercise during VEST monitoring. A cardiopulmonary exercise test was performed a few days after. The VEST data were averaged for 1 minute. Stroke volume, cardiac output, and systemic vascular resistance were expressed as percent of baseline. Exercise tolerance was assessed as maximal oxygen consumption.

RESULTS

In eight HCM patients (36%) with an abnormal blood-pressure response, end-systolic volume increased more (52% +/- 21% vs 31% +/- 28%, P = .012), and the ejection fraction (-31% +/- 17% vs -14% +/- 22%, P = .029) and stroke volume (-21% +/- 21% vs 3% +/- 28%, P = .026) fell more, than in patients with normal response. Cardiac output increased less in the former patients (49% +/- 44% vs 94% +/- 44%, P = .012). Systemic vascular resistance decreased similarly, irrespective of blood-pressure response (-28% +/- 26% vs -34% +/- 26%, P = N.S.). Percent of maximal predicted oxygen consumption was lower in HCM patients with an abnormal blood-pressure response (63% +/- 11% vs 78% +/- 15%, P = .025).

CONCLUSIONS

In HCM patients, abnormal blood-pressure response was associated with exercise-induced LV systolic dysfunction and impairment in oxygen consumption. This may cause hemodynamic instability, associated with a high risk of sudden cardiac death.

Alcohol septal ablation for hypertrophic obstructive cardiomyopathy: a systematic review of published studies

OBJECTIVE

Alcohol septal ablation (ASA) for hypertrophic obstructive cardiomyopathy (HOCM) has emerged as a lesser invasive alternative to surgical myectomy over the past decade. The purpose of this study is to analyze all the published literature on outcomes and complications after ASA.

METHODS

MEDLINE and PubMed were searched for all available published literature on ASA (June 1996-June 2005) using the terms hypertrophic obstructive cardiomyopathy (HOCM), alcohol septal ablation for hypertrophic obstructive cardiomyopathy, alcohol septal ablation for HOCM, alcohol septal ablation (ASA), transcoronary alcohol septal ablation for hypertrophic obstructive cardiomyopathy (TASH), transcoronary alcohol septal ablation for HOCM, nonsurgical septal reduction therapy (NSRT), and percutaneous transcoronary septal myocardial ablation (PTSMA).

RESULTS

A total of 42 published studies (2,959 patients) were analyzed. Mean age was 53.5 (35.4-72) years with a mean male to female ratio of 1.17. Mean follow-up was 12.7 +/- 0.3 months (1.5-43.2). Absolute ethanol (3 mL) was injected in 1.2 septal perforator arteries. On average, serum CK peaked at 964 units. At 12 months, there was a sustained decrease in resting and provoked LVOT gradient (65.3-15.8 and 125.4-31.5 mmHg, respectively) accompanied by reduction in basal septal diameter (20.9-13.9 mm), improvement in NYHA Class (2.9-1.2), and increase in exercise capacity (325.3-437.5 seconds). Early mortality (within 30 days) was 1.5% (0.0-5.0%) and late mortality (beyond 30 days) was 0.5% (0.0-9.3%). Other complications include ventricular fibrillation (2.2%), LAD dissection (1.8%), complete heart block requiring permanent pacemaker (10.5%), and pericardial effusion (0.6%). A repeat ASA was performed on 6.6% of patients and 1.9% of patients underwent surgical myomectomy with resolution of symptoms.

CONCLUSIONS

Literature to date suggests that ASA results in acute and intermediate-term favorable clinical and echocardiographic outcomes. A randomized controlled trial is needed to compare ASA and myomectomy in order to determine which technique provides maximal benefit.

Electrocardiographic exercise stress testing: an update beyond the ST segment

Routine exercise testing is frequently ordered to evaluate a patient's cardiovascular performance. The test is more direct and less expensive than imaging technology, and derives valuable information. New variables such as dyspnea and heart rate recovery, as well as integrated scores, provide incremental value to conventional analysis of exercise-induced angina or electrocardiographic changes. Considerations relating to test accuracy in women need to be weighed. This paper seeks to make physicians aware of the current status of the test, and improve their understanding of and ability to integrate new variables and scores to more effectively manage their patients.

Left Atrial Index Is a Predictor of Exercise Capacity in Patients with Hypertrophic Cardiomyopathy

BACKGROUND

Left atrial (LA) enlargement is related to diastolic dysfunction and mitral regurgitation (MR), both of which are common in patients with hypertrophic cardiomyopathy (HCM). This study investigates the association between LA size and exercise capacity in patients with HCM.

METHODS

All HCM patients who underwent a treadmill test with direct measurement of oxygen consumption (VO2) and a standard transthoracic echocardiography within 30 days in the years 2001-2003 were identified. Patients with significant comorbidities were excluded. Exercise capacity was defined as percentage of predicted peak VO2. Clinical and echocardiographic parameters were compared with those of a group of normal subjects.

RESULTS

Compared with normal subjects, HCM patients had increased left atrial (LA) volume index (36 vs 21 mL/m2; P < .0001) and mitral E/e' ratio (14 vs 9; P < .0001); 27% of the patients had at least moderate MR. LA volume index demonstrated borderline correlation with exercise capacity (r = -.20; P = .06) but was an independent predictor of exercise capacity in a multivariate linear analysis, together with body mass index, heart rate at rest, and left ventricular end-systolic diameter. Including the parameters E/e' ratio or moderate or severe MR did not add incremental value to the model.

CONCLUSION

LA volume index, reflecting the combined influences of MR and diastolic dysfunction, was independently associated with objective measures of exercise capacity in patients with isolated HCM.

Technology Insight: transcoronary ablation of septal hypertrophy

Among patients with hypertrophic cardiomyopathy, 5-10% have outflow tract obstruction that results in symptoms refractory to medical therapy. Surgical myectomy has been the gold standard for treating these patients since the 1960s. In the past 10 years, however, alcohol septal ablation has emerged as an alternative procedure. There is growing evidence to indicate that this technique is comparable to surgical myectomy with respect to hemodynamic and functional improvement, although no randomized comparative studies exist to date. The procedure consists of injecting as mall volume of alcohol into a septal perforator under balloon occlusion,preferably after localization of the target septal branch by myocardial contrast echocardiography. Relief of the gradient is instantaneous in about 90% of patients, and further decreases might occur over time. Functional class, exercise capacity and quality of life have been shown to be improved during follow-up. The main risk of the technique is atrioventricular block, which occurs in about 10% of patients. Because of this side-effect and a steep learning curve, the technique should be performed only by experienced operators and on carefully selected patients.

Hypertrophic cardiomyopathy: state-of-the-art review, with focus on the management of outflow obstruction

Significant advances in our understanding and management of hypertrophic cardiomyopathy have been made in the last decade, as the complex genetics and phenotype-genotype correlations that characterize the disease are gradually unravelled. The well-described clinical heterogeneity of hypertrophic cardiomyopathy is now understood to be based on profound genetic variability, with at least 10 genes and over 150 mutations implicated. Several new therapeutic tools have entered clinical practice. The implantable cardioverter-defibrillator is now strongly indicated in those at high risk of sudden arrhythmic death. Our ability to abort sudden death in this subgroup has placed added emphasis on risk stratification in newly diagnosed patients. New procedures have also been developed for the relief of outflow obstruction in patients with refractory symptoms and a significant subaortic outflow gradient. Although not as efficacious as the 'gold-standard' surgical myectomy-myotomy, dual-chamber pacemaker implantation can be of modest benefit in select patients. Percutaneous transluminal septal myocardial ablation is an emerging catheter-based procedure for the relief of left ventricular outflow obstruction. Long-term follow-up data are still awaited. However, intermediate-term results suggest equivalent efficacy to surgical myectomy-myotomy.

Hemodynamic determinants of exercise-induced abnormal blood pressure response in hypertrophic cardiomyopathy

OBJECTIVES

We sought to assess the hemodynamics of exercise in patients with hypertrophic cardiomyopathy (HCM), with and without an exercise-induced abnormal blood pressure (BP) response, by ambulatory radionuclide monitoring of left ventricular (LV) function with the VEST device (Capintec Inc., Ramsey, New Jersey).

BACKGROUND

Blood pressure fails to increase >20 mm Hg during exercise in about one-third of patients with HCM. This carries a high risk of sudden death.

METHODS

Forty-three patients with HCM and 14 control subjects underwent maximal symptom-limited exercise on a treadmill during VEST. The VEST data were averaged for 1 min and analyzed at baseline, 3 min and peak exercise. The LV end-diastolic, end-systolic and stroke volumes, cardiac output and systemic vascular resistance were expressed as the percentage of baseline.

RESULTS

Ejection fraction and stroke volume fell in patients with HCM, although they increased in control subjects (p < 0.001 and p = 0.002, respectively). Cardiac output increased significantly more in control subjects than in patients with HCM (p = 0.001). In 17 patients with HCM (39%) with an abnormal BP response, ejection fraction and stroke volume fell more (p = 0.032 and p = 0.009, respectively) and cardiac output increased less (p = 0.001) than they did in patients with HCM with a normal BP response. Systemic vascular resistance decreased similarly in patients with HCM, irrespective of the BP response.

CONCLUSIONS

In patients with HCM with and without an abnormal BP response, abnormal hemodynamic adaptation to exercise was qualitatively similar but quantitatively different. An abnormal BP response was associated with exercise-induced LV systolic dysfunction. This causes hemodynamic instability, associated with a high risk of sudden cardiac death.

Role of controlled septal infarct in hypertrophic obstructive cardiomyopathy

Hypertrophic obstructive cardiomyopathy is a complex and challenging disease. Medical therapy, surgical therapy, and pacing therapy have been used with some success over the years. Nonsurgical septal reduction therapy, also called alcohol septal ablation, has been used recently as a percutaneous catheter-based intervention to improve left ventricular outflow tract obstruction and thereby improve symptoms. The reported results of this procedure have shown impressive reductions in gradient and improvement in symptoms at relatively low risk. The most common complication of the procedure, development of complete heart block requiring a permanent pacemaker, has improved in recent studies with refinements of the procedural technique. Nonsurgical septal reduction therapy has been shown to improve diastolic function, decrease left ventricular hypertrophy and mass, and cause changes at the cellular and molecular level that improve myocardial function. Reported results at 1 year follow-up continue to show benefit, and long-term studies are ongoing.

Vascular mechanisms of sudden death in hypertrophic cardiomyopathy, including blood pressure responses to exercise

Approximately a third of patients with hypertrophic cardiomyopathy fail to increase blood pressure appropriately during exercise, a consequence of an inappropriate vasodilator response in nonexercising beds, leading to an exaggerated fall in systemic vascular resistance. The precise mechanism responsible for this abnormal vascular control in hypertrophic cardiomyopathy is still unclear, but is thought to be secondary to enhanced cardiac baroreceptor activity. However, alternate or synergistic mechanisms, including enhanced release of brain natriuretic peptide, may be involved. Normal exercise blood pressure responses have been shown to have a high (97%) negative predictive accuracy for sudden death during an average follow-up of approximately 3 years, providing considerable reassurance. Patients with abnormal blood pressure responses on exercise were at markedly increased risk of sudden cardiac death, although the positive predictive accuracy during this brief follow-up period was low (15%). It is likely that vascular instability may act as a trigger for sudden cardiac death in patients with an underlying electrophysiologic substrate. Recent evidence suggests that this vascular instability may also result in hypotension during ordinary daily activity, or even at rest, and may be an important cause of syncope in hypertrophic cardiomyopathy. Further studies are required to identify mechanisms of attenuating or reversing this vascular instability. Such measures might have the potential to improve symptoms of recurrent syncope and perhaps reduce the risk of sudden cardiac death.

Percutaneous transluminal septal myocardial ablation: A new catheter-based therapy for patients with hypertrophic obstructive cardiomyopathy

Hypertrophic obstructive cardiomyopathy is a complex disorder with serious clinical implications. Percutaneous transluminal septal myocardial ablation is a promising new addition to existing therapies for this condition. It is a catheter-based approach that involves instilling alcohol into the septal branches of the left anterior descending artery to induce a 'controlled' septal myocardial infarct. The result is a decrease in thickness of the hypertrophied interventricular septum and a reduction of the left ventricular outflow tract gradient. To date, the results from several series have been promising, with improvements in haemodynamic and clinical parameters without prohibitive complication rates. In this article, the indications, technique and outcomes of this procedure are reviewed.

The importance of ventricular septal morphology in the effectiveness of dual chamber pacing in hypertrophic obstructive cardiomyopathy

It has been reported that older patients with hypertrophic obstructive cardiomyopathy (HOCM) benefited the most from dual chamber (DDD) pacing. Since in older patients the distribution of septal hypertrophy and left ventricular (LV) cavity shape differs from that in younger patients, we decided to study the efficacy of DDD pacing on the reduction of LV outflow tract (LVOT) gradient in different patterns of septal hypertrophy. We compared HOCM patients with nonreversed septal curvature, thus preserving the elliptical LV cavity contour (common in the elderly), (group I) versus patients with reversed septal curvature, deforming the LV cavity to a crescent shape (common in the young), (group II). Eighteen HOCM patients were studied (11 patients in group I and 7 patients in group II). After implantation of a DDD pacemaker, the LVOT gradient was measured using Doppler echocardiography at various programmed AV delay intervals to determine the maximal percentage decrease of LVOT gradient from baseline. The measurement was repeated after at least a 6-month follow-up (chronic DDD pacing). The baseline LVOT gradient was comparable between groups (79 +/- 28 vs 81 +/- 25 mmHg, P = 0.92). The LVOT gradient reduction at acute DDD pacing was significantly greater in group I than group II (61 +/- 18% vs 23 +/- 10%, P = 0.0001). This difference in favor of the patients from group I was maintained at midterm follow-up (69 +/- 17% vs 40 +/- 17% P = 0.0076). In conclusion, patients with normal septal curvature and preserved elliptical LV cavity shape had a greater reduction of LVOT gradient after DDD pacing than patients with reversed septal curvature deforming LV cavity. The proposed criterion assessing the septal curvature may be useful to predict the efficacy of DDD pacing in the reduction of LVOT gradient.

Percutaneous transluminal septal myocardial ablation

Percutaneous transluminal septal myocardial ablation (PTSMA) is a new, investigational, catheter-based treatment for severely symptomatic, medically refractory hypertrophic obstructive cardiomyopathy. A balloon catheter is used to cannulate and isolate the first or second septal perforator coronary artery. Following balloon inflation and intracoronary myocardial contrast echocardiography, ethyl alcohol is injected through the catheter lumen to cause proximal interventricular septum infarction and relief of outflow tract obstruction with improved patient symptoms. Septal scarring and thinning with reductions in the outflow tract gradients ensues over the following 6 to 12 weeks. Most patients have symptomatic improvement, at least moderate reductions in outflow tract gradients, and possibly improvement in exercise capacity. The most common procedural complication is the development of high-grade atrioventricular block necessitating implantation of a permanent pacemaker in 25% of patients. Compared with surgical myectomy, PTSMA has the advantage of being minimally invasive, easily repeated, and with relatively low major morbidity/mortality risk for patients with comorbid conditions. The findings from recently initiated international registries will be helpful in assessing the overall success and complication rates with PTSMA.