Alcohol septal ablation complicated by complete heart block and permanent pacemaker failure

Percutaneous septal ablation for symptomatic hypertrophic obstructive cardiomyopathy: managing the risk of procedure-related AV conduction disturbances

AIM

To provide tools for predicting the course of AV conduction disturbances after ethanol-induced septal ablation (PTSMA) for hypertrophic obstructive cardiomyopathy (HOCM).

METHODS AND RESULTS

Based on a scoring system developed 1996-1998 and including parameters from baseline ECG, heart rate profile, severity of outflow obstruction (LVOTO), peri-interventional enzyme kinetics, and peri-interventional conduction problems, the risk of permanent AV block following PTSMA was assessed in 155 consecutive HOCM patients (pts.; mean age: 53+/-13 years) between 1999 and 2004. During PTSMA with 2.1+/-0.5 ml of ethanol, transient complete AV block occurred in 71 pts. (46%). Pts. were grouped into a low, intermediate, and high risk group for permanent conduction damage, and treated accordingly (early discharge from monitoring, prolonged monitoring, early DDD-PM implantation). Permanent pacing was necessary in 11 cases (7%), 0/116 of these (0%) in the low, 4/31 (13%) in the intermediate, and 7/8 (87%) in the high-risk group. While a new right bundle branch block was the most frequent ECG finding after PTSMA, a left bundle branch block at baseline was associated with 4 of the 11 DDD-PM implantations (p<0.0001). In-hospital mortality was 0%, short-term (3-months) follow up was complete. During follow-up, AV conduction recovered in 4 pts. (46%) with a DDD-PM. New onset AV blocks did not occur. Significant improvement of symptoms was reported by 141 pts. (91%).

CONCLUSIONS

Catheter-based septal ablation is an effective non-surgical technique for reducing symptoms and outflow gradients in HOCM. The proposed scoring system appears to reliably discriminate pts. with a high risk for permanent PM dependency from those with stable AV conduction after PTSMA. Pts. with left bundle branch block at baseline should undergo DDD-PM implantation prior to ablation.

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.

Acute predictors of subacute complete heart block after alcohol septal ablation for obstructive hypertrophic cardiomyopathy

Acute and subacute complete heart block (CHB) are sequelae of alcohol septal ablation (ASA) for obstructive hypertrophic cardiomyopathy. Temporary pacemakers are routinely placed at the time of ASA, but there are no widely accepted guidelines for their management. This study examined acute predictors of subacute CHB in 52 consecutive ASA procedures in 48 patients without preexisting permanent pacemakers. Acute CHB occurred during 32 ASA procedures (62%), with the return of atrioventricular conduction on the day of ASA in all cases. New intraventricular conduction defects (IVCDs) were noted after 32 procedures (62%); in 9 of these, there was new first-degree atrioventricular block as well. CHB recurred subacutely 36 +/- 22 hours after 13 ASA procedures (25%). In 5 of these cases, there was absent or inconsistent ventricular escape rhythm. Subacute CHB did not occur in 9 cases without acute CHB during ASA or new IVCDs after ASA. Acute CHB during ASA, new IVCDs after ASA, and new first-degree atrioventricular block after ASA incrementally increased the risk for subacute CHB. In conclusion, patients with acute CHB during ASA or new IVCDs after ASA are at high risk for developing subacute CHB, sometimes without a reliable escape rhythm; these patients should therefore have temporary pacing support for > or = 48 hours after ASA or the last occurrence of CHB. Patients without acute CHB during ASA or new IVCDs after ASA are at low risk for subacute CHB.

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.