Trans-Atlantic Differences in Approach to Sudden Death Prevention in Patients With Hypertrophic Cardiomyopathy.

The American approach to predicting sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy diverges from the European method in that it relies on major risk factors independently justifying the implantation of an implantable cardioverter-defibrillator for primary prevention, whereas the European approach uses a mathematical equation to estimate a 5-year risk percentage. The aim of this review is to outline the differences between the American and European guidelines and to show how they have arisen. Furthermore, it will provide insight into the future of SCD risk prediction in patients with hypertrophic cardiomyopathy. The American SCD risk prediction method has high sensitivity but limited specificity, whereas the European method has the opposite. These differences in sensitivity and specificity likely contribute to the fact that primary prevention implantable cardioverter-defibrillator utilization is twofold higher in the United States. It is highly likely that new insights and new imaging modalities will enhance prediction models in the near future. Genotyping could potentially assume a significant role. Left ventricular global longitudinal strain was recently shown to be an independent predictor of SCD. Furthermore, after late gadolinium enhancement, additional cardiac magnetic resonance techniques such as T1 mapping and diffusion tensor imaging are showing encouraging outcomes in predicting SCD. Ultimately, it is conceivable that integrating diverse morphological and genetic characteristics through deep learning will yield novel insights and enhance SCD prediction methods.

Outcomes of Alcohol Septal Ablation in Patients With Severe Left Ventricular Outflow Tract Obstruction: A Propensity Score Matching Analysis.

BACKGROUND: The current ACC/AHA guidelines on hypertrophic cardiomyopathy (HCM) caution that alcohol septal ablation (ASA) might be less effective in patients with left ventricular outflow tract obstruction (LVOTO) ≥ 100 mm Hg. METHODS: We used a multinational registry to evaluate the outcome of ASA patients according to baseline LVOTO. RESULTS: A total of 1346 ASA patients were enrolled and followed for 5.8 ± 4.7 years (7764 patient-years). The patients with baseline LVOTO ≥ 100 mm Hg were significantly older (61 ± 14 years vs 57 ± 13 years; P < 0.01), more often women (60% vs 45%; P < 0.01), and had a more pronounced HCM phenotype than those with baseline LVOTO < 100 mm Hg. There were no significant differences in the occurrences of 30-day major cardiovascular adverse events in the 2 groups. After propensity score matching (2 groups, 257 pairs of patients), the long-term survival was similar in both groups (P = 0.10), the relative reduction of LVOTO was higher in the group with baseline LVOTO ≥ 100 mm Hg (82 ± 21% vs 73 ± 26%; P < 0.01), but the residual resting LVOTO remained higher in this group (23 ± 29 mm Hg vs 13 ± 13 mm Hg; P < 0.01). Dyspnoea (NYHA functional class) at the most recent clinical check-up was similar in the 2 groups (1.7 ± 0.7 vs 1.7 ± 0.7; P = 0.85), and patients with baseline LVOTO ≥ 100 mm Hg underwent more reinterventions (P = 0.02). CONCLUSIONS: After propensity matching, ASA patients with baseline LVOTO ≥ 100 mm Hg had similar survival and dyspnoea as patients with baseline LVOTO < 100 mm Hg, but their residual LVOTO and risk of repeated procedures were higher.

Outcomes of Patients With Hypertrophic Obstructive Cardiomyopathy and Pacemaker Implanted After Alcohol Septal Ablation.

BACKGROUND: Atrioventricular block is a frequent major complication after alcohol septal ablation (ASA). OBJECTIVES: The aim of this study was to evaluate the outcomes of patients with implanted permanent pacemaker (PPM) related to a high-grade atrioventricular block after ASA for hypertrophic obstructive cardiomyopathy. METHODS: We used a multinational registry (the Euro-ASA registry) to evaluate the outcome of patients with PPM after ASA. RESULTS: A total of 1,814 patients were enrolled and followed up for 5.0 ± 4.3 years (median = 4.0 years). A total of 170 (9.4%) patients underwent PPM implantation during the first 30 days after ASA. Using propensity score matching, 139 pairs (n = 278) constituted the matched PPM and non-PPM groups. Between the matched groups, there were no long-term differences in New York Heart Association functional class (1.5 ± 0.7 vs 1.5 ± 0.9, P = 0.99) and survival (log-rank P = 0.47). Patients in the matched PPM group had lower long-term left ventricular (LV) outflow gradient (12 ± 12 mm Hg vs 17 ± 19 mm Hg, P < 0.01), more pronounced LV outflow gradient decrease (81% ± 17% vs 72% ± 35%, P < 0.01), and lower LV ejection fraction (64% ± 8% vs 66% ± 8%, P = 0.02) and were less likely to undergo reintervention (re-ASA or myectomy) (log-rank P = 0.02). CONCLUSIONS: Patients with hypertrophic obstructive cardiomyopathy treated with ASA have a 9% probability of PPM implantation within 30 days after ASA. In long-term follow-up, patients with PPM had similar long-term survival and New York Heart Association functional class but lower LV outflow gradient, a more pronounced LV outflow gradient decrease, a lower LV ejection fraction, and a lower likelihood of reintervention compared with patients without PPM.

Prediction of Sudden Cardiac Arrest After Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy: ASA-SCARRE Risk Score.

This study aimed to derive a new score, the Alcohol Septal Ablation-Sudden Cardiac ARREst (ASA-SCARRE) risk score, that can be easily used to evaluate the risk of sudden cardiac arrest events (sudden cardiac death, resuscitation, or appropriate implantable cardioverter-defibrillator discharge) after alcohol septal ablation (ASA) in patients with hypertrophic obstructive cardiomyopathy. We analyzed 1,834 patients from the Euro-ASA registry (49% men, mean age 57 ± 14 years) who were followed up for 5.0 ± 4.3 years (9,202 patient-years) after ASA. A total of 65 patients (3.5%) experienced sudden cardiac arrest events, translating to 0.72 events per 100 patient-years. The independent predictors of sudden cardiac arrest events were septum thickness before ASA (hazard ratio 1.09 per 1 mm, 95% confidence interval 1.04 to 1.14, p <0.001) and left ventricular outflow tract (LVOT) gradient at the last clinical checkup (hazard ratio 1.01 per 1 mm Hg, 95% confidence interval 1.01 to 1.02, p = 0.002). The following ASA-SCARRE risk scores were derived and independently predicted long-term risk of sudden cardiac arrest events: "0" for both LVOT gradient <30 mmHg and baseline septum thickness <20 mm; "1" for LVOT gradient ≥30 mm Hg or baseline septum thickness ≥20 mm; and "2" for both LVOT gradient ≥30 mm Hg and baseline septum thickness ≥20 mm. The C statistic of the ASA-SCARRE risk score was 0.684 (SE 0.030). In conclusion, the ASA-SCARRE risk score may be a useful and easily available clinical tool to predict risk of sudden cardiac arrest events after ASA in patients with hypertrophic obstructive cardiomyopathy.

Loss of cardiac synchronization due to automatic sense testing.

In the latest generation Biotronik cardiac resynchronization devices, cardiac resynchronization therapy (CRT) may be inadvertently interrupted due to automatic sense testing. This issue can easily be recognized during device interrogation by the "CRT interrupt warning."To avoid CRT interruption, both understanding of the algorithm and correct device programming are critical. The automatic sense testing algorithm has no built-in protection to avoid CRT interrupted pacing. When implanting this generation of devices programming needs to be adequate to avoid the occurrence of this phenomenon.

Alcohol dose in septal ablation for hypertrophic obstructive cardiomyopathy.

BACKGROUND: The aim of this study was to evaluate short- and long-term outcomes related to dose of alcohol administered during alcohol septal ablation (ASA) in patients with hypertrophic obstructive cardiomyopathy (HOCM). Current guidelines recommend using 1-3 mL of alcohol administered in the target septal perforator artery, but this recommendation is based more on practical experience of interventionalists rather than on systematic evidence. METHODS: We included 1448 patients and used propensity score to match patients who received a low-dose (1.0-1.9 mL) versus a high-dose (2.0-3.8 mL) of alcohol during ASA. RESULTS: The matched cohort analysis comprised 770 patients (n = 385 in both groups). There was a similar occurrence of 30-day post-procedural adverse events (13% vs. 12%; p = 0.59), and similar all-cause mortality rates (0.8% vs. 0.5%; p = 1) in the low-dose group and the high-dose group, respectively. In the long-term follow-up (5.4 ± 4.5 years), a total of 110 (14%) patients died representing 2.58 deaths and 2.64 deaths per 100 patient-years in the low dose and the high dose group (logrank, p = 0.92), respectively. There were no significant differences in the long-term dyspnea and left ventricular outflow gradient between the two groups. Patients treated with a low-dose of alcohol underwent more subsequent septal reduction procedures (logrank, p = 0.04). CONCLUSIONS: Matched HOCM patients undergoing ASA with a low-dose (1.0-1.9 mL) or a high-dose (2.0-3.8 mL) of alcohol had similar short- and long-term outcomes. A higher rate of repeated septal reduction procedures was observed in the group treated with a low-dose of alcohol.

Effectiveness of alcohol septal ablation for hypertrophic obstructive cardiomyopathy in patients with late gadolinium enhancement on cardiac magnetic resonance.

BACKGROUND: According to European guidelines, alcohol septal ablation (ASA) for hypertrophic obstructive cardiomyopathy (HOCM) may be less effective in patients with extensive septal scarring on cardiac magnetic resonance (CMR). This study aimed to analyze the impact of late gadolinium enhancement (LGE) on CMR on the effectiveness of ASA. METHOD: We conducted an observational retrospective study involving adult patients with symptomatic drug-refractory HOCM who underwent CMR before ASA at two European centres from May 2010 through June 2019. Patients were compared in binary format based on LGE presence. Moreover, a subanalysis focused on patients with septal fibrosis was performed. The effectiveness of ASA was evaluated by echocardiographic, ECG and clinical findings. RESULTS: Of the 113 study patients, 54 (48%) had LGE on CMR. The LGE quantification performed in 29 patients revealed septal fibrosis in 17. The mean follow-up was 4.4 ±â€¯2.6 years. Baseline parameters were similar between groups except for basal septal thickness that was greater in LGE+ group (21.1 ±â€¯3.9 mm for LGE+ vs. 19.2 ±â€¯3.2 mm for LGE-: p = .005). ASA improved symptoms in all groups and reduced left ventricular outflow tract obstruction (LVOTO) (delta gradient reduction: LGE+: 62 ±â€¯37.3%; septal LGE+: 75.6 ±â€¯20.8%; LGE-: 72.5 ±â€¯21.0%). However, 13% of the LGE+ and 2% of the LGE- group had residual LVOTO above 30 mmHg (p = .027). CONCLUSION: ASA was effective in all patients with HOCM, whether they had LGE on CMR or not and whether they had septal fibrosis or not.

Alcohol septal ablation in patients with severe septal hypertrophy.

OBJECTIVE: The current guidelines suggest alcohol septal ablation (ASA) is less effective in hypertrophic obstructive cardiomyopathy (HOCM) patients with severe left ventricular hypertrophy, despite acknowledging that systematic data are lacking. Therefore, we analysed patients in the Euro-ASA registry to test this statement. METHODS: We compared the short-term and long-term outcomes of patients with basal interventricular septum (IVS) thickness <30 mm Hg to those with ≥30 mm Hg treated using ASA in nine European centres. RESULTS: A total of 1519 patients (57±14 years, 49% women) with symptomatic HOCM were treated, including 67 (4.4%) patients with IVS thickness ≥30 mm. The occurrence of short-term major adverse events were similar in both groups. The mean follow-up was 5.4±4.3 years and 5.1±4.1 years, and the all-cause mortality rate was 2.57 and 2.94 deaths per 100 person-years of follow-up in the IVS <30 mm group and the IVS ≥30 mm group (p=0.047), respectively. There were no differences in dyspnoea (New York Heart Association class III/IV 12% vs 16%), residual left ventricular outflow tract gradient (16±20 vs 16±16 mm Hg) and repeated septal reduction procedures (12% vs 18%) in the IVS <30 mm group and IVS ≥30 mm group, respectively (p=NS for all). CONCLUSIONS: The short-term results and the long-term relief of dyspnoea, residual left ventricular outflow obstruction and occurrence of repeated septal reduction procedures in patients with basal IVS ≥30 mm is similar to those with IVS <30mm. However, long-term all-cause and cardiac mortality rates are worse in the ≥30 mm group.

Short- and long-term outcomes of alcohol septal ablation for hypertrophic obstructive cardiomyopathy in patients with mild left ventricular hypertrophy: a propensity score matching analysis.

AIMS: Based on European guidelines, alcohol septal ablation (ASA) for hypertrophic obstructive cardiomyopathy (HOCM) is indicated only in patients with interventricular septum (IVS) thickness >16 mm. The aim of this study was to evaluate the short- and long-term outcomes in ASA patients with mild hypertrophy (IVS ≤ 16 mm). METHODS AND RESULTS: We retrospectively evaluated 1505 consecutive ASA patients and used propensity score to match 172 pairs (344 patients) in groups IVS ≤ 16 mm or IVS > 16 mm. There was no occurrence of post-ASA ventriculoseptal defect in the whole cohort (n = 1505). Matched patients had 30-day mortality rate 0% in IVS ≤ 16 mm group and 0.6% in IVS > 16 mm group (P = 1). Patients in IVS ≤ 16 mm group had more ASA-attributable early complications (16% vs. 9%; P = 0.049), which was driven by higher need for pacemaker implantation (13% vs. 8%; P = 0.22). The mean follow-up was 5.4 ± 4.3 years and the annual all-cause mortality rate was 1.8 and 3.2 deaths per 100-patient-years in IVS ≤ 16 group and IVS > 16 group, respectively (log-rank test P = 0.04). There were no differences in symptom relief and left ventricular (LV) gradient reduction. Patients with IVS ≤ 16 mm had less repeated septal reduction procedures (log-rank test P = 0.03). CONCLUSION: Selected patients with HOCM and mild hypertrophy (IVS ≤ 16 mm) had more early post-ASA complications driven by need for pacemaker implantation, but their long-term survival is better than in patients with IVS >16 mm. While relief of symptoms and LV obstruction reduction is similar in both groups, a need for repeat septal reduction is higher in patients with IVS > 16 mm.

Long-term outcome of conservative and invasive treatment in patients with hypertrophic obstructive cardiomyopathy.

Background and objective: Treatment for patients with hypertrophic obstructive cardiomyopathy (HOCM) can be either conservative or invasive (alcohol septal ablation (ASA) and myectomy). As there is no clear consensus on the long-term effects of these different strategies, the aim was to compare the long-term outcome in a large tertiary referral university hospital. Methods: We retrospectively included 106 HOCM patients. Twenty-nine (27.4%) patients were treated conservatively, 25 (23.6%) underwent ASA and 52 (49.0%) myectomy. Endpoints were all-cause mortality and sudden cardiac death (SCD)-related events (including SCD, aborted SCD and appropriate ICD shocks). Kaplan-Meier survival analysis and Cox proportional hazard regression models were used. Results: The mean follow-up period was 7.7 ± 4.9 years. Overall, there was no significant difference in survival between the three treatment strategies (p = 0.7). Annual rates of SCD-related events at 5 years and the complete follow-up period were significantly higher (p = 0.034) after conservative treatment (4.9%/year and 2.7%/year, respectively) compared to ASA (0.9%/year, 0.5%/year) and myectomy (1.0%/year, 0.6%/year). Independent predictors of SCD-related events were: conservative treatment (HR 10.66; 1.88-60.55), a known mutation (HR 9.36; 1.43-61.20), left ventricular wall thickness (LVWT) > 30 mm (HR 6.48; 1.05-39.92) and non-sustained VT (HR 16.82; 2.29-123.29). Invasive treatment resulted in a significant higher proportion of patients requiring pacing (p = 0.033). Conclusions: Long-term mortality rates for patients with HOCM are similarly low between treatment groups. However, conservative treatment was associated with SCD-related events, as were known mutations, increased LVWT and non-sustained VT. Invasive treatment was associated with a higher need for implantation of a pacemaker.

Effect of impaired cardiac conduction after alcohol septal ablation on clinical outcomes: insights from the Euro-ASA registry.

AIMS: We analysed the impact of bundle branch block (BBB) and pacemaker (PM) implantation on symptoms and survival after alcohol septal ablation (ASA) in patients with hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS: Among 1416 HCM patients from the Euro-ASA registry, 58 (4%) patients had a PM and 64 (5%) patients had an implantable cardioverter-defibrillator (ICD) before ASA. At latest follow-up (5.0 ± 4.0 years) after ASA, 118 (8%) patients had an ICD and 229 (16%) patients had a PM. In patients without an implantable device prior to ASA 13% had a PM and 5% had an ICD implanted following ASA. New onset BBB was present in 44% (right BBB in 31%) of patients without previous BBB. At latest follow-up, we found no associations between BBB and New York Heart Association (NYHA) Class 3-4 [odds ratio (OR) 0.98, 95% confidence interval (CI) 0.63-1.51; P = 0.91] or Canadian Cardiovascular Society (CCS) Class 3-4 (OR 1.5, CI 0.32-6.7; P = 0.62), respectively, and no associations between PM and NYHA Class 3-4 (OR 1.2, CI 0.70-2.0; P = 0.52) or CCS 3-4 (OR 1.3, CI 0.24-6.6; P = 0.79), respectively. The survival after ASA was not reduced in patients with BBB [hazard ratio (HR) 0.73, CI 0.53-1.01; P = 0.06] or PM (HR 0.78, CI 0.52-1.17; P = 0.24). CONCLUSIONS: Development of BBB or need for a PM after ASA in patients with obstructive HCM was not associated with inferior symptomatic outcome or reduced survival, thus concerns for the negative impact of impaired cardiac conduction on the clinical outcome after ASA were not confirmed.

Effect of Institutional Experience on Outcomes of Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy.

BACKGROUND: The current American College of Cardiology Foundation/American Heart Association guidelines on hypertrophic cardiomyopathy state that institutional experience is a key determinant of successful outcomes and lower complication rates of alcohol septal ablation (ASA). The aim of this study was to evaluate the safety and efficacy of ASA according to institutional experience with the procedure. METHODS: We retrospectively evaluated 1310 patients with symptomatic obstructive hypertrophic cardiomyopathy who underwent ASA and were divided into 2 groups. The first-50 group consisted of the first consecutive 50 patients treated at each centre, and the over-50 group consisted of patients treated thereafter (patients 51 and above). RESULTS: In the 30-day follow-up, there was a significant difference in the occurrence of major cardiovascular adverse events (21% in the first-50 group vs 12% in the over-50 group; P < 0.01), which was driven by the occurrence of cardiovascular deaths (2.1% vs 0.4%; P = 0.01) and implanted pacemakers (15% vs 9%; P < 0.01). In the long-term follow-up (5.5 ± 4.1 years), the first-50 group was associated with a significantly higher occurrence of major adverse events (P < 0.01) and higher cardiovascular mortality (P < 0.01). Also, patients in the first-50 group were more likely to self-report dyspnea of New York Heart Association class III/IV (16% vs 10%), to have a left ventricular outflow gradient > 30 mm Hg (16% vs 10%) at the last clinical check-up (P < 0.01 for both), and a probability of repeated septal reduction therapy (P = 0.03). CONCLUSIONS: An institutional experience of > 50 ASA procedures was associated with a lower occurrence of ASA complications, better cardiovascular survival, better hemodynamic and clinical effect, and less need for repeated septal reduction therapy.

Validation of the HCM Risk-SCD model in patients with hypertrophic cardiomyopathy following alcohol septal ablation.

Aims: The HCM Risk-SCD model for prediction of sudden cardiac death (SCD) in hypertrophic cardiomyopathy recommended by the 2014 European Society of Cardiology (ESC) guidelines has not been validated after septal reduction therapy. The aim of this study was to validate the HCM Risk-SCD model in patients undergoing alcohol septal ablation (ASA) and to compare its performance to previous models. Methods and result: A total of 844 ASA patients without prior SCD event were included. The primary endpoint was a composite of SCD and appropriate implantable cardioverter defibrillator (ICD) therapy, identical to the HCM Risk-SCD endpoint. A distinction between periprocedural (≤30 days) and long-term (>30 days) SCD was made to discern procedure-related adverse arrhythmic events caused by the ASA-induced myocardial infarction from long-term SCD risk. Twenty patients reached the SCD endpoint within the first 30 days. During a follow-up of 6.5 ± 4.2 years, another 46 patients reached the SCD endpoint. The predicted 5-year SCD risk according to the HCM Risk-SCD model was 5.1%, and the observed 5-year SCD risk was 4.0%. The C-statistics for the use of the HCM Risk-SCD model was 0.61 (P = 0.02), the C-statistics for the use of the 2003 American College of Cardiology/ESC guidelines was 0.59 (P = 0.051), and the C-statistic for the use of the 2011 American College of Cardiology Foundation/American Heart Association guidelines was 0.58 (P = 0.054). Maximal left ventricular wall thickness, syncope after ASA, and fulfilling the 2014 ESC recommendations for primary ICD implantation according to the HCM Risk-SCD model, respectively, predicted SCD during long-term follow-up. Conclusion: The HCM Risk-SCD model can be used for SCD prediction in patients undergoing ASA.

New Developments in Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy is the leading cause of sudden death in young individuals and an important cause of heart failure at any age. In this review we discuss advances in investigation and management of this heterogenous disease. Improved cardiac imaging has allowed us to detail many of the structural abnormalities whereas the use of new techniques, predominantly in cardiac magnetic resonance imaging, has given us a greater insight in to tissue architecture, mechanism of contractile abnormalities, and function. Risk stratification remains challenging because of the low event rate in clinical studies. Multicentre registries have improved risk stratification for sudden cardiac death and multiple models can be used to aid decision-making for implantable defibrillator therapy. We discuss the current state of nonsurgical septal reduction therapy and results of multicentre registries. New approaches to septal reduction therapy including refinement of alcohol ablation and noncoronary interventions such as radiofrequency ablation of the septum show great promise. Surgical myectomy remains a major part of treatment; a greater recognition of abnormalities of the mitral valve apparatus can allow improved surgical options. Myocardial perfusion abnormalities are known to predict adverse outcome in hypertrophic cardiomyopathy and we discuss underlying mechanisms and relevance to management. The off-label use of currently licensed medicines such as ranolazine, perhexiline, calcium channel blockers, and renin-angiotensin system antagonists are discussed. A novel approach to medical treatment of the underlying sarcomeric disorder has been investigated and shows great potential.

Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy: A Word of Endorsement.

Twenty years after the introduction of alcohol septal ablation (ASA) for the treatment of obstructive hypertrophic cardiomyopathy, the arrhythmogenicity of the ablation scar appears to be overemphasized. When systematically reviewing all studies comparing ASA with myectomy with long-term follow-up, (aborted) sudden cardiac death and mortality rates were found to be similarly low. The focus should instead shift toward lowering the rate of reinterventions and pacemaker implantations following ASA because, in this area, ASA still seems inferior to myectomy. Part of the reason for this difference is that ASA is limited by the route of the septal perforators, whereas myectomy is not. Improvement may be achieved by: 1) confining ASA to hypertrophic cardiomyopathy centers of excellence with high operator volumes; 2) improving patient selection using multidisciplinary heart teams; 3) use of (3-dimensional) myocardial contrast echocardiography for selecting the correct septal (sub)branch; and 4) use of appropriate amounts of alcohol for ASA.

Outcomes of Alcohol Septal Ablation in Younger Patients With Obstructive Hypertrophic Cardiomyopathy.

OBJECTIVES: The aim of this study was to describe the safety and outcomes of alcohol septal ablation (ASA) in younger patients with obstructive hypertrophic cardiomyopathy. BACKGROUND: The American College of Cardiology Foundation/American Heart Association guidelines reserve ASA for older patients and patients with serious comorbidities. Data on long-term age-specific outcomes after ASA are scarce. METHODS: A total of 1,197 patients (mean age 58 ± 14 years) underwent ASA for obstructive hypertrophic cardiomyopathy. Patients were divided into young (≤50 years), middle-age (51 to 64 years), and older (≥65 years) groups. RESULTS: Thirty-day mortality and pacemaker implantation rates were lower in young compared with older patients (0.3% vs. 2% [p = 0.03] and 8% vs. 16% [p < 0.001], respectively). Ninety-five percent of young patients were in New York Heart Association functional class I or II at last follow-up. During a mean follow-up period of 5.4 ± 4.2 years, 165 patients (14%) died. Annual mortality rates of young, middle-age, and older patients were 1%, 2%, and 5%, respectively (p < 0.01). Annual adverse arrhythmic event rates were similar in the 3 age groups at about 1% (p = 0.90). Independent predictors of mortality in young patients were age, female sex, and residual left ventricular outflow tract gradient. Additionally, young patients treated with ≥2.5 ml alcohol had a higher all-cause mortality rate (0.6% vs. 1.4% per year in patients treated with <2.5 ml, p = 0.03). CONCLUSIONS: ASA in younger patients with obstructive hypertrophic cardiomyopathy was safe and effective for relief of symptoms at long-term follow-up. The authors propose that the indication for ASA can be broadened to younger patients.