Alcohol septal ablation for the treatment of hypertrophic obstructive cardiomyopathy. A multicenter North American registry.

OBJECTIVES: The purpose of the study is to identify the predictors of clinical outcome (mortality and survival without repeat septal reduction procedures) of alcohol septal ablation for the treatment of patients with hypertrophic obstructive cardiomyopathy. BACKGROUND: Alcohol septal ablation is used for treatment of medically refractory hypertrophic obstructive cardiomyopathy patients with severe outflow tract obstruction. The existing literature is limited to single-center results, and predictors of clinical outcome after ablation have not been determined. Registry results can add important data. METHODS: Hypertrophic obstructive cardiomyopathy patients (N = 874) who underwent alcohol septal ablation were enrolled. The majority (64%) had severe obstruction at rest, and the remaining had provocable obstruction. Before ablation, patients had severe dyspnea (New York Heart Association [NYHA] functional class III or IV: 78%) and/or severe angina (Canadian Cardiovascular Society angina class III or IV: 43%). RESULTS: Significant improvement (p < 0.01) occurred after ablation (~5% in NYHA functional classes III and IV, and 8 patients in Canadian Cardiovascular Society angina class III). There were 81 deaths, and survival estimates at 1, 5, and 9 years were 97%, 86%, and 74%, respectively. Left anterior descending artery dissections occurred in 8 patients and arrhythmias in 133 patients. A lower ejection fraction at baseline, a smaller number of septal arteries injected with ethanol, a larger number of ablation procedures per patient, a higher septal thickness post-ablation, and the use beta-blockers post-ablation predicted mortality. CONCLUSIONS: Variables that predict mortality after ablation, include baseline ejection fraction and NYHA functional class, the number of septal arteries injected with ethanol, post-ablation septal thickness, beta-blocker use, and the number of ablation procedures.

Defibrillation thresholds in hypertrophic cardiomyopathy.

BACKGROUND: Defibrillation threshold (DFT) testing is performed in part to ensure an adequate safety margin for the termination of spontaneous ventricular arrhythmias. Left ventricular mass is a predictor of high DFTs, so patients with hypertrophic cardiomyopathy (HCM) are often considered to be at risk for increased defibrillation energy requirements. However, there are little prospective data addressing this issue. OBJECTIVE: To assess DFTs in patients with HCM and evaluate the clinical predictors of elevated DFTs. METHODS: Eighty-nine consecutive patients with HCM and 600 control patients with ischemic or nonischemic cardiomyopathy underwent a uniform modified step-down DFT testing protocol. DFT was compared between the control and HCM populations. Predictors of elevated DFT were evaluated in the HCM group. RESULTS: There was no difference in DFT between HCM and control groups (10.4 ± 5.8 J vs 11.2 ± 5.6 J, respectively). Among patients with HCM, clinical parameters such as left ventricular ejection fraction, interventricular septal thickness, left ventricular mass, and QRS duration were not predictive of an elevated DFT. Only 3 patients (3.4%) with HCM had a DFT >20 J. CONCLUSION: Patients with HCM do not have elevated DFTs as compared to more typical populations undergoing implantable cardioverter-defibrillator implant; high-energy devices or complex lead systems are not needed routinely in this population.

Implantable cardioverter-defibrillator therapy for primary prevention of sudden death after alcohol septal ablation of hypertrophic cardiomyopathy.

OBJECTIVES: The purpose of this study was to examine the effects of alcohol septal ablation (ASA) on ventricular arrhythmias among patients with obstructive hypertrophic cardiomyopathy (HCM), as measured by appropriate implantable cardioverter-defibrillator (ICD) discharges. BACKGROUND: Alcohol septal ablation is an effective therapy for patients with symptomatic HCM. However, concern has been raised that ASA may be proarrhythmic secondary to the iatrogenic scar created during the procedure. The impact of ASA on ventricular arrhythmias has not been well described. METHODS: This prospective study included 123 consecutive patients with obstructive HCM who underwent ASA and had an ICD implanted for primary prevention of sudden cardiac death (SCD). The ICDs were implanted based on commonly accepted risk factors for SCD in the HCM population. Data from ICD interrogations during routine follow-up were collected. RESULTS: Nine appropriate ICD shocks were recorded over a mean follow-up of 2.9 years in the cohort, which had a mean of 1.5 +/- 0.9 risk factors for SCD. Using Kaplan-Meier survival analysis, the estimated annual event rate was 2.8% over 3-year follow-up. There were no significant differences in the incidence of risk factors between patients who did and did not receive appropriate shocks. CONCLUSIONS: The annual rate of appropriate ICD discharges after ASA is low and less than that reported previously for primary prevention of SCD in HCM. This suggests that ASA is not proarrhythmic. Traditional SCD risk factors did not predict ICD shocks in this cohort.

Follow-up of alcohol septal ablation for symptomatic hypertrophic obstructive cardiomyopathy the Baylor and Medical University of South Carolina experience 1996 to 2007.

OBJECTIVES: This study sought to determine the long-term outcome of alcohol septal ablation (ASA). BACKGROUND: There are inadequate data on the long-term outcome of ASA for symptomatic hypertrophic obstructive cardiomyopathy (HOCM). METHODS: Six hundred and twenty-nine patients were enrolled consecutively (1996 to 2007) and 98.4% (n = 619) underwent ASA with 92% follow-up in 2007. Evaluation included deaths, procedural complications, pacemaker requirement, repeat ASA, and myectomy/valve surgery. Follow-up parameters included angina (Canadian Cardiovascular Society score), dyspnea (New York Heart Association functional class), exercise time, and echocardiographic indices (septal thickness, ejection fraction, resting and provoked gradients). RESULTS: Ethanol (2.6 +/- 1.0 ml) was injected into 1.3 +/- 0.5 septal arteries, inducing a septal infarct. Complications included death 1% (n = 6), permanent pacemaker requirement 8.2% (n = 52), coronary dissection 1.3% (n = 8), and worsening mitral regurgitation 0.3% (n = 2). The mean follow-up was 4.6 +/- 2.5 years (range: 3 months to 10.2 years). During follow-up, New York Heart Association functional class decreased from 2.8 +/- 0.6 to 1.2 +/- 0.5 (p < 0.001); Canadian Cardiovascular Society angina score decreased from 2.1 +/- 0.9 to 1.0 +/- 0 (p < 0.001); and exercise time increased from 4.8 +/- 3.3 to 8.2 +/- 1.0 (p < 0.001) min. The resting and provoked left ventricular outflow tract gradients decreased progressively (p < 0.001) and remained low during follow-up. The septal thickness decreased from 2.1 +/- 0.5 cm to 1.0 +/- 0.1 cm (p < 0.001) and the ejection fraction decreased from 68 +/- 9% to 62 +/- 3% (p < 0.001). The survival estimates at 1, 5, and 8 years were 97%, 92%, and 89%, respectively. CONCLUSIONS: The initial benefits of ASA were maintained during follow-up.

Depression, anxiety, and quality of life in patients with obstructive hypertrophic cardiomyopathy three months after alcohol septal ablation.

Patients with obstructive hypertrophic cardiomyopathy are presumed to have poor quality of life (QOL) and distress related to their cardiac symptoms and functional limitations. Alcohol septal ablation (ASA) is designed to improve heart function and reduce cardiac symptoms. The purpose of this study was to examine psychosocial factors and QOL in patients with obstructive hypertrophic cardiomyopathy before and 3 months after ASA. Twenty-two adult participants (mean age 57 +/- 14 years, 59% women, 100% Caucasian, 67% married) were recruited during their initial evaluations or scheduled index hospitalizations for ASA. Psychosocial and medical measures were collected before and 3 months after ASA. The results indicated that before ASA, 57% of patients reported clinically relevant levels of depression (Center for Epidemiologic Studies Depression Scale score >16), symptoms of anxiety, and reduced QOL. Repeated-measures analyses of variance revealed that ASA is an effective procedure in reducing disease severity (i.e., peak left ventricular outflow tract gradient, septal thickness, posterior wall thickness) (p = 0.001 to 0.05), depression (p = 0.005), and anxiety (p = 0.029) and improving cardiac-specific QOL (p < 0.001) and generic physical health-related QOL (p = 0.009). Changes in satisfaction with life, optimism, and generic mental health-related QOL were not significant (p = 0.143 to 0.899). In conclusion, significant psychological distress and compromised well-being were present in this sample of pre-ASA patients with obstructive hypertrophic cardiomyopathy. After ASA, significant reductions in psychological distress and improvements in well-being and echocardiographic parameters indicating disease severity were demonstrated. These results suggest that patients perceived broad health benefits from ASA in short-term follow-up.

Outcome of surgical myectomy after unsuccessful alcohol septal ablation for the treatment of patients with hypertrophic obstructive cardiomyopathy.

OBJECTIVES: We sought to determine the outcome of myectomy after unsuccessful alcohol ablation. BACKGROUND: Alcohol septal ablation results in symptomatic improvement and a reduction in dynamic obstruction in most hypertrophic obstructive cardiomyopathy patients. However, a few patients remain with severe symptoms and obstruction and need surgery. The outcome of these cases is not well known. METHODS: The medical records of 375 patients who underwent alcohol ablation at our institution were reviewed. Twenty patients (5.3%, mean age 53 +/- 18 years, 17 women) subsequently needed surgical myectomy. The New York Heart Association (NYHA) functional class, angina class, exercise duration, left ventricular outflow tract (LVOT) gradient, ejection fraction, and septal thickness were tabulated. The anatomy and distribution of the septal perforator arteries were examined. RESULTS: After ablation, NYHA functional class (3 to 2.5; p < 0.05) and LVOT gradient (93 +/- 23 mm Hg to 71 +/- 26 mm Hg; p < 0.05) were slightly improved, without a change in exercise duration (171 +/- 124 s to 168 +/- 148 s; p > 0.5). Myectomy was performed at 19 +/- 15 months after ablation. There was no operative mortality, but permanent pacing was needed in 2 patients after surgery, and 3 other cases needed pacing before, or as a complication of, alcohol ablation. A significant improvement was noted, with the NYHA functional class decreasing to 1, exercise duration increasing to 423 +/- 171 s, and LVOT gradient decreasing to 6 +/- 11 mm Hg (all p < 0.05 versus post-alcohol ablation). CONCLUSIONS: Myectomy can be successfully performed after failed alcohol ablation, but with a higher incidence of heart block than in cases where only surgery is performed. Otherwise, alcohol ablation does not appear to adversely affect surgical outcome.

Effectiveness of percutaneous intervention for patients with obstructive hypertrophic cardiomyopathy and coronary artery disease.

Seven patients with obstructive hypertrophic cardiomyopathy and single-vessel coronary artery disease underwent percutaneous revascularization of the coronary lesion in addition to alcohol septal ablation therapy for dynamic outflow tract obstruction. One year later, there was a significant reduction of dynamic left ventricular outflow tract obstruction and no clinical evidence of restenosis.

A prospective follow-up of alcohol septal ablation for symptomatic hypertrophic obstructive cardiomyopathy--the Baylor experience (1996-2002).

BACKGROUND: There is a paucity of data on the long-term outcome of alcohol septal ablation (ASA) for symptomatic hypertrophic obstructive cardiomyopathy (HOCM). HYPOTHESIS: The study was undertaken to evaluate the longer-term outcome of ASA therapy for symptomatic HOCM. METHODS: In all, 137 patients were enrolled consecutively (1996-1999) and 130 (95%) (74 men, 56 women, aged 51 +/- 17 years) underwent ASA and had serial prospective follow-up for up to 5 years (mean follow-up 3.6 +/- 1.4 years). Evaluation included angina (Canadian Cardiovascular Society [CCS] score), dyspnea (New York Heart Association [NYHA] class), duration of exercise on treadmill, and echocardiographic indices. RESULTS: Ethanol (3.5 +/- 1.5 cc), injected into 1.5 +/- 0.6 arteries, induced a mean peak plasma creatine kinase (CK) of 1676 +/- 944 units. Complications of procedures included death 1.5% (2/130), heart block requiring permanent pacemaker 13% (17/130), and coronary dissection 4.4% (6/130). Baseline versus last follow-up visit: NYHA class decreased from 3.0 +/- 0.4 to 1.2 +/- 0.6 (p < 0.01); CCS angina score from 2.0 +/- 0.8 to 0.08 +/- 0.4 (p < 0.01); and duration of exercise increased from 322 +/- 207 to 443 +/- 200 s (p < 0.01). Resting left ventricular outflow tract gradient at baseline versus last follow-up visit showed a decrease from 74 +/- 30 to 4 +/- 13 (p < 0.01), and the dobutamine-provoked gradient of 88 +/- 29 decreased to 21 +/- 21 (p < 0.01) mmHg. All-cause mortality over the duration of follow-up was 7.7% (10) giving an annual rate of 2.1%, and cardiac mortality was 2.3% (3) reflecting an annual rate of 0.6%. CONCLUSIONS: Alcohol septal ablation decreased symptoms and improved exercise performance, indicating that it is an effective procedure for symptomatic HOCM.

Plasma monitoring of the myocardial specific tissue inhibitor of metalloproteinase-4 after alcohol septal ablation in hypertrophic obstructive cardiomyopathy.

BACKGROUND: The overall goal of this study was to develop an assay procedure for measuring the relative abundance of tissue inhibitor of metalloproteinase (TIMP)-4 in plasma, and then use this approach to determine dynamic changes of TIMP-4 levels in hypertrophic obstructive cardiomyopathic (HOCM) patients after an acute myocardial infarction (MI). Matrix metalloproteinases (MMPs) contribute to tissue remodeling and are regulated by the endogenous TIMPs. TIMP-4 is observed to be expressed in higher abundance in the myocardium when compared with other types of tissues. Recent clinical studies have measured changes in TIMP-4 levels; however, these studies have been limited to measuring this protein from myocardial tissue samples. To date, no studies have monitored TIMP-4 levels in plasma samples. METHODS AND RESULTS: Plasma TIMP-4 levels were examined (by semiquantitative immunoblotting) in normal (n=18) and HOCM (n=16) patients after alcohol-induced MI. Serial measurements of plasma TIMP-4 levels were examined up to 60 hours after alcohol-induced MI in patients with HOCM. Unglycosylated plasma TIMP-4 levels increased 250% in the HOCM patients when compared with normal controls. Total plasma TIMP-4 levels decreased by 20% at 30 hours after alcohol-induced MI. CONCLUSIONS: The unique results demonstrated that an induction of a controlled MI, specifically through alcohol ablation, caused a reduction in plasma TIMP-4 levels in HOCM patients after alcohol-induced MI that would facilitate myocardial remodeling in the early post-MI setting.

Management of prominent iris vascular tufts causing recurrent spontaneous hyphema.

PURPOSE: To report the management of recurrent, spontaneous hyphema associated with florid iris vascular tufts in a patient presenting for cataract surgery. METHODS: Interventional case report and review of the literature; presentation of clinical findings, iris angiography, and the argon laser regimen used to minimize potential corneal complications with increased total treatment energy. RESULTS: An 80-year-old man with a 20-year history of bilateral, recurrent, spontaneous hyphema associated with extensive iris vascular tufts presented with visually significant cataracts. Serial argon laser photocoagulation treatment of the prominent, circumferential iris vascular tufts of the left eye arrested further episodes of spontaneous hyphema and facilitated uneventful cataract surgery. Argon laser parameters were titrated to therapeutic effect during the initial treatment sessions, and sectoral photocoagulation of the circumferential vascular tufts was performed during a 5-month period to accommodate increased laser power and energy. The total energy required to complete treatment of the extensive lesions was substantially more than that in similar previous reports; however, no adverse corneal complications were associated with the laser therapy. CONCLUSIONS: This case appears to represent the first description of chronic, bilateral, recurrent spontaneous hyphema associated with iris vascular tufts. Argon laser treatment of symptomatic iris vascular tufts promotes resolution of recurrent, spontaneous hyphema and may serve to mitigate the risk of hemorrhage from these lesions during subsequent intraocular surgery. Conservative management of increased total treatment energy may minimize the potential risk of corneal decompensation with argon laser therapy.

Sustained ventricular tachycardia following alcohol septal ablation for hypertrophic obstructive cardiomyopathy.

A 49-year-old man with a history of hypertrophic obstructive cardiomyopathy (HOCM) presented in sustained monomorphic ventricular tachycardia (SMVT) 8 days post-alcohol septal ablation. A dual chamber implantable cardioverter defibrillator ICD was implanted and the patient experienced another episode of VT 3 weeks later, which was terminated by an ICD shock. This case demonstrates probable scar-induced reentrant VT post-alcohol septal ablation, a likely rare but hypothesized complication of this procedure.

Predictors of outcome after alcohol septal ablation therapy in patients with hypertrophic obstructive cardiomyopathy.

BACKGROUND: Alcohol septal ablation (ASA) therapy results in clinical and hemodynamic improvement in patients with hypertrophic obstructive cardiomyopathy. However, a subset remains symptomatic afterward, requiring additional procedures. We sought to examine the determinants of an unsatisfactory outcome, defined as unchanged symptoms with <50% reduction of baseline left ventricular outflow tract (LVOT) gradient. METHODS AND RESULTS: Of 173 consecutive hypertrophic obstructive cardiomyopathy patients who underwent ASA, 39 had an unsatisfactory outcome after the first procedure. Patients with an unsatisfactory outcome had a higher baseline LVOT gradient, fewer septal arteries injected with ethanol, lower peak creatine kinase (CK), smaller septal area opacified by contrast echocardiography, and higher residual gradient in the catheterization laboratory after ASA (all P<0.05). Symptoms, septal thickness, mitral regurgitation severity, and ventricular function were not determinants of outcome. On multiple logistic regression, LVOT gradient reduction after ASA in the catheterization laboratory to > or =25 mm Hg (OR, 5.5; P=0.01) and peak CK <1300 U/L (OR, 2.5; P=0.04) were the independent predictors of an unsatisfactory outcome. CONCLUSIONS: The residual LVOT gradient in the catheterization laboratory and peak CK leak after ASA are the independent predictors of ASA outcome.

Detection of histoplasma capsulatum DNA in lesions of chronic ocular histoplasmosis syndrome.

OBJECTIVE: To evaluate choroidal lesions in histological sections from the enucleated eye of a patient with chronic ocular histoplasmosis syndrome for the presence of Histoplasma capsulatum DNA. METHODS: Laser-capture microdissection was used to procure cells from macular and midperipheral choroidal lesions in a deparaffinized hematoxylin-eosin-stained section prepared from the enucleated left eye of a patient with an ipsilateral choroidal melanoma and bilateral chronic histoplasmosis syndrome. The captured cells were initially subjected to polymerase chain reaction (PCR) amplification using a pair of primers unique to each end of the nucleotide sequences that are complementary to the DNA known to flank the internal transcribed spacer regions of the ribosomal RNA genes of H capsulatum. This product was then reamplified using a second set of internally situated nested primers. The results were compared with a positive control sample of H capsulatum DNA and with a negative microdissected sample from noninflamed choroid in the same slide. RESULTS: Products of H capsulatum DNA were identified in both samples of microdissected tissue and the positive control. They were absent in the negative control. CONCLUSION: The observations provide molecular biological evidence linking the chronic choroidal lesions to earlier infection by H capsulatum.

A new mutation (Leu569Arg) within exon 13 of the TGFBI (BIGH3) gene causes lattice corneal dystrophy type I.

PURPOSE: To describe an American family with lattice corneal dystrophy type I, which associates with a novel mutation, Leu569Arg, of the TGFBI (BIGH3) gene. DESIGN: Experimental study. METHODS: Genomic DNA was extracted from buccal epithelial cells of four affected members of an American family with lattice corneal dystrophy type I. All 17 exons of the TGFBI gene were evaluated by PCR amplification and direct sequencing. Clinical and histologic data were also collected. RESULTS: Three generations of this family have been positively diagnosed with lattice corneal dystrophy, indicating autosomal dominant inheritance. We identified a heterozygous point mutation that associates with the disease phenotype. The single base-pair substitution (T1753G) results in an amino acid substitution (Leu569Arg) in exon 13 of the TGFBI gene. CONCLUSIONS: Substitution of arginine for leucine at position 569 of the TGFBI gene results in a form of lattice corneal dystrophy that is phenotypically similar to other genetically distinct forms of type I disease. This is the first report of disease correlated with changes in exon 13 of the TGFBI gene.

Nonsurgical septal reduction therapy for hypertrophic obstructive cardiomyopathy: short-term results in 50 consecutive procedures.

BACKGROUND: Nonsurgical septal reduction therapy (NSRT) has been shown to improve left ventricular outflow tract (LVOT) gradients, decrease septal thickness, and improve symptoms in patients with hypertrophic obstructive cardiomyopathy (HOCM). The major complication of this procedure has been the development of complete heart block (CHB) requiring permanent pacemaker implantation, which has been reported in up to 33% of patients in early studies. Since this procedure was first reported, there have been refinements in the technique such as the use of echocardiographic contrast material to localize the site of infarction, slower injection of alcohol, as well as improvement in balloon technology. HYPOTHESIS: We sought to determine the results of NSRT using echocardiographic contrast localization, slow injection of alcohol, and short balloon length. We theorized that the incidence CHB would be lower than earlier reported results using these refined techniques. METHODS: We performed 50 NSRT procedures on 46 patients using echocardiographic contrast localization, slow alcohol injection, and currently available balloons. Patients had an echocardiogram before, immediately after NSRT, and at 3 months, and a treadmill test before and at 3 months after NSRT. In the hospital, patients were observed for the development of CHB or other complications, and infarct size was determined by serial creatine kinase (CK) measurements. RESULTS: There was a decrease in the LVOT gradient from 84.2 (+/- 30.8) mmHg at baseline, to 18.5 (+/- 14.8) mmHg immediately after NSRT (p < 0.001). At 3 months, the gradient was not statistically different at 22.7 (+/- 22.2) mmHg 0.27). The septal thickness decreased from 2.21 (+/- 0.66) cm at baseline, to 1.67 (+/- 0.51) cm at 3 months (p < 0.001). New York Heart Association symptom class improved from 3.2 (+/- 0.4) at baseline, to 1.1 (+/- 0.6) at 3 months (p < 0.001). Mean treadmill time in 30 patients was 235 (+/- 142) s at baseline, to 367 (+/- 159) s at 3 months (p < 0.001). Of the 50 procedures, 45 were performed in patients without a previously placed permanent pacemaker or intracardiac cardioverter defibrillator, only 3 (6.7%) of the 45 developed complete heart blocks required permanent pacing. While only three patients in the series had a preexisting left bundle-branch block (LBBB), two of the three patients who required a permanent pacemaker had an LBBB before the prcoedure. CONCLUSION: Using contrast echocardiographic localization, slow injection of alcohol, and shorter balloon catheters, there continues to be excellent improvement in LVOT gradients, septal thickness, and symptoms, with a reduced incidence of CHB requiring permanent pacemaker implantation. Left bundle-branch block appears to be a strong predictor for the development of CHB after NSRT.

Complete heart block: determinants and clinical impact in patients with hypertrophic obstructive cardiomyopathy undergoing nonsurgical septal reduction therapy.

OBJECTIVES: The purpose of this paper is to examine the incidence and determinants of permanent complete heart block (CHB) after nonsurgical septal reduction therapy (NSRT), and to evaluate the clinical impact of permanent pacemaker (PPM) placement. BACKGROUND: Nonsurgical septal reduction therapy with ethanol improves the clinical and hemodynamic parameters in patients with symptomatic hypertrophic obstructive cardiomyopathy. Complete heart block is a common complication after NSRT. METHODS: The database of 261 consecutive patients who underwent NSRT at Baylor College of Medicine was reviewed. Clinical variables that were considered as possible determinants for CHB after NSRT were: age, gender, New York Heart Association (NYHA) functional class, left ventricular outflow tract (LVOT) gradient at rest or with provocation, septal thickness, and baseline exercise duration. For electrocardiographic (ECG) variables, the presence of first-degree atrioventricular (AV) block, bifascicular block, left bundle branch block, atrial fibrillation, and left ventricular hypertrophy were analyzed. In addition, the volume of ethanol injected, the method of administration of ethanol (i.e., bolus vs. slow injection [over 30 to 60 s]), number of septal arteries occluded, use of myocardial echocardiography, and infarct size as determined by peak creatine kinase level. RESULTS: Of 261 consecutive patients, 37 had PPM or automatic implantable cardiac defibrillator placed before NSRT. Of the remaining 224 patients, 31 (14%) developed CHB after the procedure. Multivariate logistic regression analysis showed that female gender (odds ratio [OR] 4.3; P = 0.02), bolus injection of ethanol (OR 51; P = 0.004), injecting more than one septal artery (OR 4.6; P = 0.016), the presence of left bundle branch block (OR 39; P = 0.002), and first-degree AV block (OR 14; P = 0.001) on the baseline ECG are independent predictors of CHB after NSRT. Patients requiring PPM placement had a similar improvement in their NYHA functional class, septal thickness reduction, LVOT gradient reduction, and improvement of exercise capacity when compared with patients who did not require pacing. CONCLUSIONS: Multiple demographic, electrocardiographic, and technical factors seem to increase the risk of CHB after NSRT. Patients with CHB after NSRT derive similar clinical and hemodynamic benefit to patients who did not require permanent pacing.