Performance, safety, and biocompatibility of a novel PFO closure device in a long-term porcine model.

BACKGROUND: As the catheter-based device closure of the patent foramen ovale (PFO) is expanding, novel devices aim to address the limitations of first-generation occluders (e.g. bulk, erosion, dislodgment). The second-generation device from Encore Medical (Eagan, MN, USA) features an articulating frame structure which allows the device to better conform to atrial anatomies, has lower disc thickness and metal mass/surface area, and is fully retrievable at any point in the procedure. The aim of the study was to evaluate the feasibility and safety of a novel low-profile, fully retrievable, Encore PFO closure device in the animal model. METHODS: Six swine underwent implantation of the novel PFO occluder under fluoroscopic and intra-cardiac echocardiography guidance and survived for 140 days. Interim transthoracic echocardiography (TTE) was conducted on Day 29. Following terminal angiography and TTE at 140 days, the hearts were subjected to gross and histopathologic analysis. RESULTS: All animals were successfully implanted and survived for 140 days. Interim TTE revealed proper device retention with no blood flow across the septum or thrombus in any of the animals. X-ray and pathology results showed preserved implant integrity with no fractures, and complete integration of the devices into the septum with complete re-endothelialization and nearly complete coverage by a mature, relatively thin neoendocardium. No surface fibrin deposition or thrombosis was reported. CONCLUSIONS: In the standard porcine model, device retention and biocompatibility remained favorable following structural and functional device modifications exemplified by the second-generation PFO occluder from Encore Medical, including marked reduction of metal mass.

Feasible stenting of a large septal perforator providing a sizeable coronary collaterals.

While coronary artery disease involving the septal perforator branches presents similar to diseases of major coronary arteries, management can present a challenge. Owing to their relatively small size, performing interventional procedures is often impractical in terms of selecting appropriate devices. Although larger septal perforator branches have been managed percutaneously, similar to major vessels, long-term sequelae and clinical effectiveness have been indeterminate. We present our experience in managing a patient with a stenosed septal perforator branch and challenging comorbidities.

The curious case of an isolated right coronary artery aneurysm complicated by thrombosis and distal embolization.

A 40-year-old male patient with no significant medical history was admitted with an inferior ST-segment elevation myocardial infarction. Primary percutaneous coronary intervention revealed a right coronary artery aneurysm, with no evidence of significant coronary disease. We support the hypothesis of aneurysmal thrombus formation with distal embolization.

Long-Term Survival After Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy: A 16-Year Experience.

BACKGROUND: Alcohol septal ablation (ASA) is an accepted treatment for medically refractory hypertrophic obstructive cardiomyopathy (HOCM). The procedural and medium-term outcomes have been reassuring. The iatrogenic targeted septal infarction has raised theoretical concerns about risk of arrhythmia and long-term survival. In this study, we describe the long-term survival in a large cohort of patients from a single referral center and the iterative improvement in procedural technique since its inception. METHODS: This cohort includes 580 consecutive patients who underwent 664 ASA procedures between the years 1999 and 2015. Procedural details and outcomes are described. Long-term survival is compared with expected survival of demographically similar controls. RESULTS: Fifty-four percent were women and 85% were Caucasian. At the time of ablation, mean age was 57 ± 15 years, septal thickness was 2.1 ± 0.5 cm, and left ventricular outflow tract (LVOT) gradient was 72 ± 40 mm Hg at rest and 102 ± 58 mm Hg with Valsalva provocation. Mean follow-up was 8.0 ± 4.3 years. LVOT gradient reduction >50% was achieved in 94% of patients with reduction in New York Heart Association functional class scores and increase in exercise treadmill duration. Procedural mortality was 0.9%. Over the 16-year period, survival estimates at 1, 5, 10, and 15 years were 98%, 92%, 84%, and 81%, respectively, which are comparable to demographically similar controls. The standardized mortality ratio was 0.84 (95% confidence interval, 0.66-1.06); P=.09. CONCLUSIONS: ASA appears to be a safe and effective treatment for symptomatic HOCM refractory to medical therapy with long-term survival comparable to a demographically similar United States population.

Predicting complete heart block after alcohol septal ablation for hypertrophic cardiomyopathy using a risk stratification model and clinical tool.

BACKGROUND: Alcohol septal ablation (ASA) is a proven method of septal reduction for patients with drug refractory, symptomatic hypertrophic obstructive cardiomyopathy (HOCM). This procedure is associated with a 6.5-11% risk of complete heart block (CHB). OBJECTIVE: The aim of this study is to determine factors that predict CHB and to develop a clinical tool for risk stratification of patients. METHODS: Patients were enrolled into an ongoing ASA study. A total of 636 patient procedures were included, 527 of whom were used in the development of the prediction tool, and 109 of whom were used for independent validation. Multivariate analysis was performed with odds ratios used to develop the clinical prediction tool. This was then internally and externally validated. RESULTS: Of the 527 in the prediction cohort, 46 developed CHB. The predictors of CHB were age ≥50 years, pre-ASA left bundle branch block (LBBB), transient procedural high-grade block, post-ASA PR prolongation ≥68 ms, and new bifascicular block. An 11-point clinical prediction tool was developed to classify these factors. Internal validation using a receiver operating characteristic curve revealed an area under the curve of 0.88 for the clinical prediction tool. External validation using 109 contemporary patients revealed a 98% negative predictive value, 24% positive predictive value, 75% sensitivity, and 81% specificity in high-risk patients. CONCLUSION: Among patients undergoing ASA, the risk of CHB can be predicted with easily obtained clinical and electrocardiographic factors. This clinical prediction tool allows identification of high-risk patients who may benefit from additional monitoring and therapy.

Relation of Lymphangiogenic Factor Vascular Endothelial Growth Factor-D to Elevated Pulmonary Artery Wedge Pressure.

Lymphatic flow is augmented in states of chronic heart failure (cHF). However, the biological mechanism driving increased lymphatic flow capacity (lymphangiogenesis) in cHF is unknown. Recent studies have indicated that vascular endothelial growth factors (VEGF-A, -C, and -D) are involved in lymphangiogenesis. This study examined the association between VEGF-A, -C, and -D levels, invasively measured hemodynamics, and heart failure symptoms. Subjects who underwent clinically indicated right heart catheterization at Medical University of South Carolina between 12/2016 and 7/2018 were eligible for inclusion. These subjects underwent clinical assessment of cHF severity (including 6MWT and KCCQ), hemodynamic assessment with right heart catheterization, laboratory studies including B-type natriuretic peptide, and concomitant measurement of VEGF-A, -C, and -D. Fifty-six patients were included for analysis. Subjects with elevated pulmonary artery wedge pressure (PAWP) had significantly higher VEGF-D levels (263 ± 415 pg/ml vs 65 ± 101 pg/ml; p = 0.02). PAWP was not associated with VEGF-A or VEGF-C levels. When stratified by VEGF-D, subjects with elevated VEGF-D had clinical and hemodynamic characteristics associated with worse HF severity (lower ejection fraction, higher b-type natriuretic peptide, higher PAWP, lower cardiac output), but were not more symptomatic by Kansas City Cardiomyopathy Questionnaire scores and had similar 6-minute walk test distance compared with subjects with lower VEGF-D. Subjects with an elevated VEGF-D were more likely to have a diagnosis of heart failure for >3 years. In conclusion, VEGF-D is associated with elevated PAWP in cHF, and elevated VEGF-D may mitigate cHF symptoms.

Transcatheter Interatrial Shunt Device for the Treatment of Heart Failure With Preserved Ejection Fraction (REDUCE LAP-HF I [Reduce Elevated Left Atrial Pressure in Patients With Heart Failure]): A Phase 2, Randomized, Sham-Controlled Trial.

BACKGROUND: In nonrandomized, open-label studies, a transcatheter interatrial shunt device (IASD, Corvia Medical) was associated with lower pulmonary capillary wedge pressure (PCWP), fewer symptoms, and greater quality of life and exercise capacity in patients with heart failure (HF) and midrange or preserved ejection fraction (EF ≥40%). We conducted the first randomized sham-controlled trial to evaluate the IASD in HF with EF ≥40%. METHODS: REDUCE LAP-HF I (Reduce Elevated Left Atrial Pressure in Patients With Heart Failure) was a phase 2, randomized, parallel-group, blinded multicenter trial in patients with New York Heart Association class III or ambulatory class IV HF, EF ≥40%, exercise PCWP ≥25 mm Hg, and PCWP-right atrial pressure gradient ≥5 mm Hg. Participants were randomized (1:1) to the IASD versus a sham procedure (femoral venous access with intracardiac echocardiography but no IASD placement). The participants and investigators assessing the participants during follow-up were blinded to treatment assignment. The primary effectiveness end point was exercise PCWP at 1 month. The primary safety end point was major adverse cardiac, cerebrovascular, and renal events at 1 month. PCWP during exercise was compared between treatment groups using a mixed-effects repeated measures model analysis of covariance that included data from all available stages of exercise. RESULTS: A total of 94 patients were enrolled, of whom 44 met inclusion/exclusion criteria and were randomized to the IASD (n=22) and control (n=22) groups. Mean age was 70±9 years, and 50% were female. At 1 month, the IASD resulted in a greater reduction in PCWP compared with sham control (P=0.028 accounting for all stages of exercise). Peak PCWP decreased by 3.5±6.4 mm Hg in the treatment group versus 0.5±5.0 mm Hg in the control group (P=0.14). There were no peri-procedural or 1-month major adverse cardiac, cerebrovascular, and renal events in the IASD group and 1 event (worsening renal function) in the control group (P=1.0). CONCLUSIONS: In patients with HF and EF ≥40%, IASD treatment reduces PCWP during exercise. Whether this mechanistic effect will translate into sustained improvements in symptoms and outcomes requires further evaluation. CLINICAL TRIAL REGISTRATION: URL: https://clinicaltrials.gov. Unique identifier: NCT02600234.

Left ventricular end-diastolic pressure affects measurement of fractional flow reserve.

BACKGROUND: Fractional flow reserve (FFR), the hyperemic ratio of distal (Pd) to proximal (Pa) coronary pressure, is used to identify the need for coronary revascularization. Changes in left ventricular end-diastolic pressure (LVEDP) might affect measurements of FFR. METHODS AND MATERIALS: LVEDP was recorded simultaneously with Pd and Pa during conventional FFR measurement as well as during additional infusion of nitroprusside. The relationship between LVEDP, Pa, and FFR was assessed using linear mixed models. RESULTS: Prospectively collected data for 528 cardiac cycles from 20 coronary arteries in 17 patients were analyzed. Baseline median Pa, Pd, FFR, and LVEDP were 73 mmHg, 49 mmHg, 0.69, and 18 mmHg, respectively. FFR<0.80 was present in 14 arteries (70%). With nitroprusside median Pa, Pd, FFR, and LVEDP were 61 mmHg, 42 mmHg, 0.68, and 12 mmHg, respectively. In a multivariable model for the entire population LVEDP was positively associated with FFR such that FFR increased by 0.008 for every 1-mmHg increase in LVEDP (beta=0.008; P<0.001), an association that was greater in obstructed arteries with FFR<0.80 (beta=0.01; P<0.001). Pa did not directly affect FFR in the multivariable model, but an interaction between LVEDP and Pa determined that LVEDP's effect on FFR is greater at lower Pa. CONCLUSIONS: LVEDP was positively associated with FFR. The association was greater in obstructive disease (FFR<0.80) and at lower Pa. These findings have implications for the use of FFR to guide revascularization in patients with heart failure. SUMMARY FOR ANNOTATED TABLE OF CONTENTS: The impact of left ventricular diastolic pressure on measurement of fractional flow reserve (FFR) is not well described. We present a hemodynamic study of the issue, concluding that increasing left ventricular diastolic pressure can increase measurements of FFR, particularly in patients with FFR<0.80 and lower blood pressure.

Comparison of lipid deposition at coronary bifurcations versus at nonbifurcation portions of coronary arteries as determined by near-infrared spectroscopy.

Atherosclerosis has been shown to develop preferentially at sites of coronary bifurcation, yet culprit lesions resulting in ST-elevation myocardial infarction do not occur more frequently at these sites. We hypothesized that these findings can be explained by similarities in intracoronary lipid and that lipid and lipid core plaque would be found with similar frequency in coronary bifurcation and nonbifurcation segments. One hundred seventy bifurcations were identified, 156 of which had comparative nonbifurcation segments proximal and/or distal to the bifurcation. We compared lipid deposition at bifurcation and nonbifurcation segments in coronary arteries using near-infrared spectroscopy (NIRS), a novel method for the in vivo detection of coronary lipid. Any NIRS signal for the presence of lipid was found with similar frequency in bifurcation and nonbifurcation segments (79% vs 74%, p = NS). Lipid core burden index, a measure of total lipid quantity indexed to segment length, was similar across bifurcation segments as well as their proximal and distal controls (lipid core burden index 66.3 ± 106, 67.1 ± 116, and 66.6 ± 104, p = NS). Lipid core plaque, identified as a high-intensity focal NIRS signal, was found in 21% of bifurcation segments, and 20% of distal nonbifurcation segments (p = NS). In conclusion, coronary bifurcations do not appear to have higher levels of intracoronary lipid or lipid core plaque than their comparative nonbifurcation regions.

Alcohol septal ablation for obstructive hypertrophic cardiomyopathy: outcomes in young, middle-aged, and elderly patients.

OBJECTIVES: We compared the efficacy and safety of alcohol septal ablation (ASA) for obstructive hypertrophic cardiomyopathy (HCM) in young, middle-aged, and elderly patients. BACKGROUND: Intersociety guidelines suggest based on limited evidence that young patients with medically refractory symptoms of obstructive HCM should undergo surgical myectomy while elderly patients may be more appropriate for ASA. METHODS: Data for 360 patients undergoing 389 ASAs were prospectively collected and retrospectively analyzed according to age. RESULTS: Young (<45 years), middle-aged (45-64 years), and elderly (≥65 years) patients comprised 28, 40, and 32% of the study population, respectively. Young patients had thicker left ventricular septal walls at baseline, and elderly patients had more comorbidity and dyspnea. Resting, mean left ventricular outflow tract gradients (LVOTGs) were similar across the age groups at baseline (62, 66, and 68 mm Hg, respectively; P = NS for all comparisons). LVOTGs and dyspnea were significantly and similarly improved in all age groups immediately after ASA and through 12 months of follow-up (P < 0.001 for before and after comparisons; P = NS for intergroup comparisons). Complication rates were similar for young and middle-aged patients but higher for elderly patients (9.1 and 6.3% vs. 20.8%, respectively; P ≤ 0.016 for elderly vs. others). Mortality rates for young and middle-aged patients were lower than for elderly patients, but the differences were not statistically significant. CONCLUSIONS: Patients undergoing ASA had significant and similar improvements in LVOTGs and symptoms regardless of age. Procedural complications were increased in elderly patients, who had numerically but not statistically significantly higher mortality rates.

Comparison of percutaneous coronary intervention safety before and during the establishment of a transradial program at a teaching hospital.

This study sought to examine the safety of percutaneous coronary intervention (PCI) before and during de novo establishment of a transradial (TR) program at a teaching hospital. TR access remains underused in the United States, where cardiology fellowship programs continue to produce cardiologists with little TR experience. Establishment of TR programs at teaching hospitals may affect PCI safety. Starting in July 2009 a TR program was established at a teaching hospital. PCI-related data for academic years 2008 to 2009 (Y1) and 2009 to 2010 (Y2) were prospectively collected and retrospectively analyzed. Of 1,366 PCIs performed over 2 years, 0.1% in Y1 and 28.7% in Y2 were performed by TR access. No major complications were identified in 194 consecutive patients undergoing TR PCI, and combined bleeding and vascular complication rates were lower in Y2 versus Y1 (0.7% vs 2.0%, p = 0.05). Patients treated in Y2 versus Y1 and by TR versus transfemoral approach required slightly more fluoroscopy but similar contrast volumes and had similar procedural durations, lengths of stay, and predischarge mortality rates. PCI success rates were 97% in Y1, 97% in Y2, and 98% in TR cases. TR PCIs were performed by 13 cardiology fellows and 9 attending physicians, none of whom routinely performed TR PCI previously. In conclusion, de novo establishment of a TR program improved PCI safety at a teaching hospital. TR programs are likely to improve PCI safety at other teaching hospitals and should be established in all cardiology fellowship training programs.

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.

Takotsubo cardiomyopathy in a patient with previously undiagnosed hypertrophic cardiomyopathy with obstruction.

Takotsubo cardiomyopathy (TCM) is usually characterized by left ventricular anteroapical dysfunction in the absence of significant coronary disease commonly precipitated by an emotional or stressful trigger. Hypertrophic cardiomyopathy (HCM) is usually diagnosed on the basis of symptoms, family history, echocardiography, or by the presence of a characteristic murmur. We report a unique case of TCM occurring in a patient with previously undiagnosed HCM with left ventricular outflow tract (LVOT) obstruction who presented with an acute coronary syndrome and ultimately underwent successful alcohol septal ablation. The potential pathophysiologic correlations are discussed.

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.

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.

Significant coronary artery stenosis: comparison on per-patient and per-vessel or per-segment basis at 64-section CT angiography.

PURPOSE: To prospectively evaluate the accuracy of 64-section computed tomographic (CT) coronary angiography for assessing significant stenosis on a global and segmental level, by using conventional coronary artery angiography as the reference standard. MATERIALS AND METHODS: This study was HIPAA compliant and had local institutional review board approval. Patients gave informed consent. Patients suspected of having coronary artery disease (CAD) underwent both conventional coronary catheter angiography and contrast material-enhanced retrospectively electrocardiographically gated 64-section multi-detector row CT of the coronary arteries. Two experienced observers analyzed all CT scans for signs of CAD (stenosis of 0%, or=50%) stenosis in CAD with an accuracy of 89%. On a per-segment and per-vessel basis, diagnostic accuracy is still impaired, primarily by limited spatial resolution.

Does two-segment image reconstruction at 64-section CT coronary angiography improve image quality and diagnostic accuracy?

PURPOSE: To prospectively evaluate the effect of single- versus two-segment image reconstruction on image quality and diagnostic accuracy at 64-section multidetector computed tomographic (CT) coronary angiography by using conventional coronary angiography as the reference standard. MATERIALS AND METHODS: The study design was approved by a human research committee; patients gave informed consent. The study was HIPAA compliant. Forty consecutive patients (22 men, 18 women; mean age, 61 years +/- 8 [standard deviation]) underwent both 64-section multidetector CT coronary angiography and conventional angiography. All data sets were reconstructed by using single- and two-segment image reconstruction algorithms, with resulting temporal resolution of 82.5-165 msec. Two experienced observers independently evaluated image quality and signs of coronary artery disease. A five-level grading scheme was used to grade stenosis (0%, <50%, <70%, <99%, 100%) and image quality (1[unacceptable] to 5[excellent]). Interobserver correlation, Spearman correlation coefficients, and diagnostic accuracy were calculated. RESULTS: Six hundred coronary artery segments were visible on conventional angiograms, of which 560 (93.3%) were seen by using single-segment and 561 (93.5%) were seen by using two-segment image reconstruction (P=.35). Mean quality scores were not significantly different (P=.22) for single- (3.1 +/- 0.9) and two-segment (3.2 +/- 0.8) reconstruction. Significantly (P=.03) better image quality was observed for two-segment reconstruction only at heart rates of 80-82 beats per minute, at which temporal resolution was approximately 83 msec. For grading coronary artery stenosis, correlation was 0.64 for single- and 0.66 for two-segment reconstruction (P=.43). Significant stenosis (>50%) was detected on a per-segment basis with 77.1% sensitivity and 98.6% specificity by using single-segment and with 79.2% sensitivity and 99.1% specificity by using two-segment image reconstruction. CONCLUSION: At heart rates of more than 65 beats per minute, use of two-segment reconstruction improves image quality at multidetector CT coronary angiography but does not significantly affect overall diagnostic accuracy compared with single-segment reconstruction.

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.