Hypertrophic obstructive cardiomyopathyalcoholseptalablationvs.myectomy:a

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1 European Heart Journal (2009) 30, doi: /eurheartj/ehp016 CLINICAL RESEARCH Heart failure/cardiomyopathy Hypertrophic obstructive cardiomyopathyalcoholseptalablationvs.myectomy:a meta-analysis Mahboob Alam, Hisham Dokainish, and Nasser M. Lakkis* Section of Cardiology, Baylor College of Medicine, Houston, TX, USA Received 9 October 2008; revised 25 December 2008; accepted 8 January 2009; online publish-ahead-of-print 19 February 2009 Aims Our purpose is to conduct a meta-analysis of all published studies comparing alcohol septal ablation (ASA) and myectomy (MM) for drug refractory hypertrophic obstructive cardiomyopathy (HOCM). Alcohol septal ablation is a less invasive alternative to MM for relief of symptoms in patients with drug refractory HOCM.... Methods An extensive search of PubMed identified five non-randomized studies comparing ASA and MM. Of 351 patients and results studied, 183 underwent ASA and 168 underwent MM. Patients undergoing ASA were older (mean age vs years, P ¼ 0.02). All patients were in New York Heart Association (NYHA) class II IV. Baseline left ventricular outflow tract (LVOT) gradient was comparable ( mmhg in ASA vs mmhg in MM, P ¼ 0.2). Although resting LVOT gradient after septal reduction therapy in both groups was,20 mmhg at follow-up, patients undergoing MM had lower LVOT gradient ( vs mmhg, P, 0.001). Patients in both groups had comparable improvement in NYHA class ( in ASA vs , P ¼ 0.2) at follow-up. A higher percentage of patients undergoing ASA required permanent pacemaker (PPM) implantation for complete heart block ( vs %, P ¼ 0.04). There was no significant in-hospital mortality difference between the two groups.... Conclusion Alcohol septal ablation and MM provide significant reduction in LVOT gradient and NYHA functional class on midterm follow-up. A higher percentage of patients required PPM after ASA. Randomized trials are needed to confirm current findings Keywords Cardiomyopathy Alcohol Ablation Myectomy Introduction Since its introduction in 1995, 1 ASA has become a widely accepted and performed procedure for relief of left ventricular outflow tract (LVOT) gradients in hypertrophic obstructive cardiomyopathy (HOCM) patients refractory to maximal medical therapy Myectomy (MM) for basal septal hypertrophy is a well established procedure with more than 40 years of experience and long term success Alcohol septal ablation (ASA) has evolved into a standardized procedure including myocardial contrast echocardiography to better localize the target septal perforator branch and lower dose of absolute ethanol injection with good outcomes and reduced complications. 2,27 32 No large, multi-centre randomized control trials exist to compare the efficacy and outcomes of these two procedures. We therefore conducted a meta-analysis of all available studies comparing these two procedures. Methods All studies comparing the clinical outcomes of patients with HOCM who required MM or ASA for drug refractory symptoms of congestive heart failure or angina pectoris were included in this meta-analysis. Search criteria An extensive literature search on PubMed was performed from 1 January 2004 through 30 September 2008 for reports comparing the * Corresponding author. Tel: þ , Fax: þ , nlakkis@bcm.edu Published on behalf of the European Society of Cardiology. All rights reserved. & The Author For permissions please journals.permissions@oxfordjournals.org.

2 ASA vs. MM for HOCM 1081 clinical outcomes after ASA or MM for HOCM. Figure 1 illustrates the details of search methodology used in this meta-analysis. A total of 5897 reports were found using a PubMed query cardiomyopathy, hypertrophic. Further limits of obstructive reduced the number of reports to Further refinement of search criteria with addition of therapy resulted in a total of 737 reports. The title and abstract of the above-mentioned reports were reviewed for terms including ASA, HOCM, transcoronary ASA for HOCM (TASH), non-surgical septal reduction therapy (NSRT), percutaneous transmyocardial septal myocardial ablation (PTSMA), MM, surgical septal reduction, and non-surgical septal reduction. After careful review only nonrandomized studies were identified that compared ASA with MM for HOCM Two independent physicians reviewed these studies for quality assessment. Variables that were assessed included accurate description of methods including inclusion criteria, exclusion criteria, differences between the patients undergoing ASA or MM, statistical tests used, and outcome measures reported along with follow-up. Since no randomized controlled trials comparing ASA and MM in patients with HOCM have been conducted to date, the best level of clinical evidence was case control studies. Two studies were excluded from final meta-analysis as they did not provide the baseline and follow-up clinical characteristics, rather focused on diastolic function of left ventricle and magnetic resonance imaging characteristics. 37,38 A total of five studies representing 351 patients undergoing ASA or MM were included ,39 Primary authors of some studies were contacted via to obtain missing data with little response. Table 1 provides an over view of study design and main characteristics of all studies included in this meta-analysis. Data analysis Statistical package SPSS version 16.0 (SPSS Inc., IL) was used to analyse baseline demographic data on these patients. Since individual patient information was not available on all patients, we report mean of means and standard error of mean. A two sided P-value of,0.05 was considered to be significant. Meta-analysis was performed using MIX version 1.7 (Bax L, Yu LM, Ikeda N, Tsuruta N, Moons KGM. MIX: Comprehensive Software for Meta-analysis of Causal Research Data - Version ). Tests of heterogeneity including Q, H, and I 2 statistics were performed. Patient population undergoing ASA or MM was homogenous for mean NYHA class, baseline LVOT gradient, and syncope or pre-syncope and therefore meta-analysis was conducted using fixed-effect ratio model for variables of interest. As the maximum number of groupwise comparisons was one fif k ¼ number of groups being tested then maximum number of groupwise comparisons will be [k*(k21)]/2 ¼ 1g and outcomes of data analysis were in agreement with prevalent literature findings, no further adjustments were made for potential inflation of a (alpha) error due to multiple Figure 1 Search criteria for inclusion in current meta-analysis.

3 1082 Table 1 Summary of studies included in meta-analysis Variable Nagueh et al.... Firoozi et al.... Van der Lee et al.... Qin et al.... Ralph-Edwards et al.... ASA MM ASA MM ASA MM ASA MM ASA MM... Study design Case Control Case Control Case Control Case Control Case Control n M:F 1.5:1 1.2:1 0.4:1 1.6:1 0.9:1 1.7:1 Mean age (years) Follow-up 12 m 12 m m m 12 m 12 m 3 m 3 m years years NYHA Baseline II (4); III VI I II (9); III IV II (14); III (6) II (15); III (8); IV Dyspnoea (40/ Dyspnoea (42/ (37) (32) (1) 78%) 88%) Follow-up I (36); II (5) I (32); II (8); III I (10); II (7); III I (13); II (8); III (2) I(19);II(24); III(4) I(34);II(6); III(2) (1) (2) Pre-syncope/ Syncope Baseline (%) 24 (59) 23 (56) 2 (10) 5 (21) NR NR NR NR 4 (8) 18 (38) Follow-up (%) 2 (5) 7 (17) NR NR NR NR NR NR NR NR BB Baseline (%) 31 (76) 26 (63) 9 (45) 8 (33) NR NR NR NR 35 (71) 30 (68) Follow-up (%) 7 (17) 24 (59) NR NR NR NR NR NR NR NR CCB Baseline (%) 19 (46) 18 (44) 6 (30) 4 (17) NR NR NR NR NR NR Follow-up (%) 1 (2) 8 (20) NR NR NR NR NR NR NR NR LVOTG (mmhg) Baseline Follow-up NR NR IVSd (mm) Baseline Follow-up NR NR LVEF(%)/FS(%) Baseline / / NR NR Follow-up / / NR NR Peak VO 2 (ml/kg/ min) Baseline NR NR NR NR NR NR Follow-up NR NR NR NR NR NR PPM Baseline (%) 9 (22) 16 (39) None None NR NR NR NR NR NR Follow-up (%) 9 (22) 1 (2) 3 (15) 1 (4.2) NR NR 6 (24) 2 (8) NR NR ICD implantation Secondary 1 (2) 1 (2) NR NR 2 (4.7) NR NR NR NR NR prevention (%) In-hospital mortality 1 (2) None None 1 (4.2) 2 (4.7) None None None None None (%) Late mortality (%) None None 1 (5) None None None None None 5 (7.4) None ASA, alcohol septal ablation; MM, myectomy; NYHA, New York Heart Association; LVOTG, left ventricular outflow tract gradient; LVEF, left ventricular ejection fraction. M. Alam et al.

4 ASA vs. MM for HOCM 1083 testing. Primary outcome variables include mortality, improvement in NYHA functional class, reduction in LVOT gradient, and reduction in septal thickness. We also evaluated procedure complications including incidence of permanent pacemaker (PPM) implantation. Results Of the 351 patients included, 183 underwent ASA and168 patients underwent MM. Four of five studies reported on patients who underwent ASA or MM during concurrent time periods and one study 39 reported on patients who underwent MM ( ) and ASA (August ) at separate time periods. Table 2 provides the baseline and follow-up characteristics of these two groups with mean, median, and quartiles along with P-values. A mean follow-up of and months was available for ASA and MM patients, respectively. All patients were symptomatic (NYHA class II IV) despite maximal medical therapy. Patients undergoing ASA were significantly older than those undergoing MM (mean age vs years, P ¼ 0.02). Patients undergoing MM had a thicker basal septum (mean difference þ1.43 mm; 95% CI to , P ¼ 0.008) at baseline. However, at follow-up there was no difference in mean septal thickness ( vs mm, P ¼ 0.95). Baseline LVOT gradient was similar at baseline and,20 mmhg at follow-up in both groups. However, patients undergoing MM had a slightly lower follow-up LVOT gradient with a mean difference of 6.6 mmhg (95% CI , P, 0.001). Table 3 provides the details of meta-analysis outcomes in this patient population. Three out of five studies did not provide mean NYHA class at follow-up with standard deviations; therefore we were unable to conduct a meta-analysis for follow-up NYHA class between the two groups. However on comparison of means using independent samples Students t-test, patients in the two groups (ASA vs. MM) had equal improvement in mean NYHA class ( vs , P ¼ 0.2) at follow-up. Figures 2 and 3 show Forest plots with 95% confidence intervals of follow-up LVOT gradient and basal septal thickness, respectively. Although only two studies documented peak oxygen consumption increase after therapy, there was no difference between the two groups ( vs % in ASA and MM, respectively, P ¼ 0.65). Baseline and follow-up echocardiographic parameters were also compared. Left ventricular ejection fraction did not decrease significantly from baseline and % to and % in ASA and MM, respectively (P ¼ 0.70). Similarly there was no difference in LV end-diastolic, LV end-systolic, and left atrial dimensions at baseline and follow-up between the two groups (Table 2). As expected, patients undergoing ASA had a higher percentage of PPM implantation for complete heart block ( vs %, P ¼ 0.04). A total of 3/183 (1.6%) patients died during hospitalization in ASA group compared with 1/168 (0.6%) of patients undergoing MM (independent samples Students t-test, P ¼ 0.2). Aetiologies for mortality in ASA group included (LAD dissection ¼1, cardiac tamponade ¼1, and refractory ventricular fibrillation after ethanol injection ¼1). The only mortality in MM group was attributed to severe post-operative congestive heart failure. A repeat procedure for recurrent increase in LVOT gradient was performed in 10/183 (5.5%) patients undergoing ASA, five of these received re-do ASA and the other five underwent MM. One out of 168 patients who underwent MM required redo-surgery. Discussion Since the first report of ASA by Sigwart, 1 this procedure has been widely accepted in the cardiovascular community. The total number of ASA performed outnumbered the surgical septal reduction by several folds. 2 In this meta-analysis both ASA and MM effectively reduce LVOT gradients as well as improve subjective and objective clinical markers such as NYHA class without significant decrease in left ventricular ejection fraction. Similar improvement was noted in basal septal thickness and both systolic and diastolic left ventricular dimensions. Surgical septal reduction seems to result in lower LVOT gradient and lower requirements for PPM implantation. None of the studies included in this meta-analysis included data on arrhythmia and sudden cardiac death reduction after either procedure. With the introduction of echocardiographic contrast use during ASA, the potential risks of inducing an apical or lateral wall infarcts due to presence of septal collaterals to these areas has essentially been eliminated in expert hands. 2,8,25,27 30 A few studies have evaluated the relationship between the volume of ethanol injected and clinical outcomes. An equivalent benefit has been reported with lesser volume of ethanol injection, i.e vs. 3 5 ml 2,5,9,14,31,32 with lower incidence of PPM implantation. These technical changes likely resulted in a lower incidence of complete heart block requiring PPM after ASA. A recent review of all published studies on ASA in HOCM patients reported mean PPM implantation rates of 10.4%. 2 Current meta-analysis includes studies published between 2001 and 2005 which has been a period of several technical improvements in the performance of ASA including use of stringent patient selection criteria, learning curve, use of myocardial contrast echocardiography, and lower volume of ethanol injection. Some of the earlier comparative studies in current meta-analysis documented a higher rate of PPM implantation compared with more recent literature. This may in part have skewed the rate of PPM implantation towards MM (18 vs. 3.4%). Of note, patients undergoing ASA also have a higher rate of repeat intervention. 2 This may be due to variable anatomy of septal branches of LAD and presence of septal collaterals which can cause technical limitations to performance and success of ASA. In contrast to MM which provides a consistent anterior septal resection without residual scar, ASA produces a scar which was shown to be variable in extent and located mostly in the upper or upper and middle septum 40 and often transmural to RV side. 38 The theoretical risk of scar-related arrhythmia in patients undergoing ASA exists but such risk has not been reported or proved. Since ASA has been performed in older patients in some centres, outcomes of ASA in younger patients are still evolving, especially long-term follow-up for sustained response (potential of collateral formation at the site of ethanol induced infarct) and the potential risk of sudden cardiac death (although the risk factors for sudden death, i.e. septal thickness, pre-syncope

5 1084 Table 2 Baseline and follow-up demographic, subjective, and objective data Variable Alcohol septal ablation (baseline) Myectomy (Baseline) P-value Alcohol septal ablation Myectomy (Follow-up) P-value (Follow-up) Mean+SD/ Centiles Mean+SD/ Centiles Mean+SD/ Centiles Mean+SD/ Centiles Median (25/50/75) Median (25/50/75) Median (25/50/75) Median (25/50/75)... Age (years) / /52.0/ / /46.0/ Follow-up / /12.0 / / /12.0/ Pre-syncope/syncope / /4.0/ / /37.5/ / /1.5/ / /12.7/ (%) NYHA class / /3.4/ / /3.2/ / /1.5/ / /1.3/ Basal septal thickness / /22.0/ / /23.0/ / /16.0 / / /17.0/ (mm) LVOT gradient / /76.0/ / /78.0/ / /21.0/ / /11.0/17/0,0.001 (mmhg) New PPM (%) / /21.9/ / /2.4/ Increase in MVO 2 (%) / /26.0/ / /35.5/ LV end-diastolic / /42.8/ / /43.0/ / /44.6/ / /44.5/ diameter (mm) LV end-systolic / /23.5/ / /23.2/ / /26.0/ / /27.8/ diameter (mm) LV ejection fraction (%) / /72.0/ / /71.0/ / /69.0/ / /68.0/ Left atrial diameter (mm) / /47.0/ / /48.0/ / /45.0/46/ / /46.0/ MVO 2, maximum oxygen consumption; PPM, permanent pacemaker; NYHA, New York Heart Association; LVOT gradient, left ventricular outflow tract gradient. M. Alam et al.

6 ASA vs. MM for HOCM 1085 Figure 2 Forest plot of follow-up left ventricular outflow tract gradient in patients undergoing alcohol septal ablation or myectomy. Patients who were treated with myectomy had a lower resting left ventricular outflow tract gradient at follow-up. Mean difference in left ventricular outflow tract gradient was 6.6 mmhg (P, 0.001). Figure 3 Forest plot of follow-up septal thickness in patients undergoing alcohol septal ablation or myectomy. Patients who underwent myectomy or alcohol septal ablation had similar follow-up basal septal thickness. Table 3 Meta-analysis details Variable Number of studies n MD a (CI) b Z c (P-value) Q d (P-value) H e (CI) b... LVOT gradient (follow-up) ( ) 3.9 (,0.001) 3.6 (0.3) 1.1 ( ) IVSd mm (follow-up) ( ) 0.2 (0.8) 7.82 (0.05) 1.6 ( ) NYHA (mean follow-up) N/A N/A N/A N/A Mortality f N/A N/A N/A N/A a MD, mean difference between ASA and MM. b CI, 95% confidence interval. c Z, standardized Z-score. d Q, Cochran s Q score for heterogeneity. e H, Higgins s test of heterogeneity. f Not enough data to conduct meaningful meta-analysis on this variable. improve after both ASA and MM with a similar proportion). A recent report by Kuhn et al. 9 shows a lower alcohol dose (,2 ml) to be an independent predictor of survival in patients undergoing ASA. In their series, patients who received lower alcohol dose had 0.6% in-hospital mortality and 1.0% annual mortality. 9 Larger-scale trials are needed to validate whether ASA is associated with higher mortality rates and whether lower volumes of ethanol can decrease mortality rates.

7 1086 M. Alam et al. Certain factors that may influence the decision of ASA or MM include presence of comorbid conditions with high surgical risk, centre and physician experience with ASA or MM, presence of other cardiac diseases requiring surgical repair (e.g. multivessel CAD requiring coronary artery by-pass graft, valvular disorders, etc.), and patient preference. Due to a higher incidence of right bundle branch block (RBBB) after ASA and left bundle branch block (LBBB) after MM, patients may be at higher risk of complete heart block after ASA (baseline LBBB) or MM (baseline RBBB). Limitations All meta-analyses suffer from publication bias, as unpublished studies are not available and the findings may thus be skewed. However, HOCM is an uncommon entity with a small number of publications available especially in the setting of ASA and MM comparison. Since individual patient data were not available for analysis; we used mean of means and standard error mean for statistical purposes. As true with any scientific report, current data may not be completely up-to-date due to studies that may not have been published of which we are unaware of at the time of manuscript submission. An average follow-up of months represents a relatively intermediate term follow-up of clinical outcomes in these patients. Most of the available literature on ASA or MM for drug-refractory HOCM has used an LVOT gradient cut off of mmhg at rest which represents an arbitrarily chosen number. For the purposes of current meta-analysis, we used a cut-off of 20 mmhg resting LVOT gradient as well. Patients undergoing MM had a slightly thicker basal septum at baseline, which may indicate a selection bias towards MM for sicker patients in this meta-analysis. No significant data were available from individual studies on reasons for technical failure in either group. Statistical validity of current meta-analysis may be biased due to absence of randomization in included studies. Conclusions Alcohol septal ablation and MM appear to provide equivalent reduction in subjective and objective measures of performance in symptomatic HOCM patients. Despite the use of echocardiographic contrast and smaller volumes of alcohol injected at a slower rate, patients undergoing ASA continue to have a higher incidence of complete heart block requiring PPM. Myectomy is a procedure which has evolved over the past five decades with significant technical improvement and better clinical outcomes. Alcohol septal ablation is still evolving, it is hoped that refinements in its technique will lead into further improvement in outcomes including lower early mortality and reduced requirement for PPM. At this point, a head-to-head randomized controlled trial comparing both treatment options in patients who can be randomized to either MM or ASA in whom both treatment options are likely to be successful should be conducted at centres of excellence in managing HOCM. 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