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Medical Policy

Policy Num:       02.002.017
Policy Name:     Transcoronary Ablation of Septal Hypertrophy (TASH)
Policy ID:          [2.002.017][Ac B M P ][2.02.14]

Last Review:      June 11, 2020
Next Review:     N/A
Issue:                   6:2020

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Transcoronary Ablation of Septal Hypertrophy (TASH)

Summary

Hypertrophic cardiomyopathy is a complex cardiac disease associated with diverse clinical, morphologic, and pathophysiologic manifestations. However, one of the most characteristic abnormalities is a hypertrophied and nondilated left ventricle, which may impair diastolic filling. When the hypertrophy results in left ventricular outflow obstruction, dyspnea, angina, syncope, or the development of congestive heart failure may occur. Pharmacologic therapies include beta-blockers or calcium-channel blockers to decrease the heart rate with a consequent prolongation in diastole and increased passive ventricular filling. If medical therapy is insufficient to control symptoms, strategies to reduce the outflow obstruction may be considered. Surgical reaction focuses on removing a small amount of myocardium at the base of the septum (myotomy-myomectomy). Dual-chamber pacing has also been explored as a means of decreasing the pressure gradient in the outflow tract, although results of randomized trials have been disappointing.

Transcoronary ablation of septal hypertrophy (TASH) has been explored as an alternative to open surgical septal resection. The technique involves infusion of ethanol through an angioplasty catheter threaded into the septal perforator branches of the left anterior descending artery to infarct and subsequently thin the bulging septum. A key component of the procedure is the identification of the target vessels. A balloon catheter is introduced into the septal branches. The balloon is inflated and contrast injected into the balloon lumen to delineate the area supplied by the septal branch and to ensure that the balloon inflation would prevent spillage of the subsequent injection of alcohol into the left anterior descending artery. Myocardial contrast echocardiography has also been used to target septal vessels. Echocardiographic contrast material may be injected into the balloon catheter and, using ultrasonography, the perfused area of the myocardium can be imaged from several different positions.

TASH may also be referred to as ethanol septal ablation.

Objective

Policy Statements

Percutaneous transluminal septal myocardial ablation may be considered medically necessary as a treatment of hypertrophic obstructive cardiomyopathy.

Policy Guidelines

Effective 12/31/07, the specific category III code for this procedure was deleted. CPT instructs that the procedure should now be coded using code 93799: Unlisted cardiovascular service or procedure.

From 2001 through 2007, the category III CPT code that specifically described TASH was:

0024T: Non-surgical septal reduction therapy (e.g., alcohol ablation) for hypertrophic obstructive cardiomypoathy; with coronary arteriograms, with or without temporary pacemaker.

The following nonspecific CPT codes may also be used by providers:

37202 Transcatheter therapy, infusion other than for thrombolysis any type

93510 Left heart catheterization; percutaneous

93511 Left heart catheterization; by cut down

93545 Injection procedure during cardiac catheterization; for selective coronary angiography

93555 Imaging supervision, interpretation and report for injection procedure during cardiac catheterization; selective coronary angiography

ICD-9 Code: 425.1 Hypertrophic obstructive cardiomyopathy

Benefit Application

BlueCard/National Account Issues

Transeptal ablation of septal hypertrophy is a specialized procedure that may require out of network referral.

Background

None

Regulatory Status

None

Rationale

Myotomy/myomectomy (also called the Morrow procedure) is considered the gold standard treatment for septal hypertrophy, based on case series that have consistently demonstrated both symptomatic and cardiodynamic improvement with an acceptable short-term mortality ranging from 2% to 5%. Patient selection criteria typically include those patients with severe outflow gradients (50 mm Hg under basal conditions) and symptomatic heart failure (New York Heart Association [NYHA] Class III or IV) that is refractory to medical therapy. Ideally, controlled clinical trials comparing the short- and long-term outcomes of myotomy/myomectomy with TASH are needed to validate the equivalency or superiority of TASH. No such studies are available, and the literature regarding TASH consists of case series with relatively short follow-up, predominantly from single institutions. Data regarding the short- and long-term outcomes of myotomy/myomectomy also consist of case series from single institutions; however, followup often exceeds 10 years. Unlike patients undergoing TASH, patients undergoing myotomy/myomectomy often undergo additional procedures, such as coronary artery bypass grafting, or mitral or aortic valve replacement. In many instances, patients undergoing myotomy/myomectomy were treated some 20 years ago, and it is likely that the morbidity and mortality has declined over the decades. In addition, all case series include patients of varying ages and with variable severity of disease, both of which may impact short- and long-term outcomes. Given these significant limitations in the available literature, the short- and long-term outcomes of myotomy/myomectomy and TASH are summarized below.

Myotomy/myomectomy The most recently published case series are reviewed here, focusing on the short-term outcomes for comparison purposes. In 1989, Mohr and colleagues summarized the outcomes of 115 patients who underwent myotomy/myomectomy between 1972 and 1987. (1) The outflow gradient was markedly reduced and 76%, 83%, and 96% of patients reported relief from dyspnea, angina, and syncope, respectively. Overall, the operative mortality was 5.2%, but only 1.2% in those less than 65 years old, rising to 15.6% in those older than 65 years. In addition, the operative mortality was 2.5% for those undergoing myotomy/myomectomy alone compared to 11.4% in those undergoing additional procedures. In 1996, Robbins and Stinson reported on a case series of 158 patients over a 22-year span. (2) The operative mortality was 3.2% for those over 60 years old and 0% for those under 60. Again the operative mortality of those undergoing myomectomy alone was lower, at 2.3%, compared to 7.4% in those undergoing combined procedures. Similar to other studies, there were improvements in NYHA functional classes and cardiodynamic improvements. In 1998, Brunner-La Schonbeck et al. reported on a case series of 110 patients spanning 30 years. (3) The perioperative mortality rate was 3.6%. The left ventricular outflow tract gradient was nearly eliminated in all patients.

TASH Clinical studies of TASH consistently report improvements in various signs and symptoms including New York Heart Association (NYHA) classification, exercise time, left ventricular pressure gradient, and septal thickness as measured by echocardiography. The larger case series are reviewed here. Seggewiss and colleagues reported on a case series of 114 patients with symptomatic hypertrophic cardiomyopathy who underwent TASH. (4) Left ventricular outflow tract gradient was reduced in 94% of patients from a mean of 73.8 mm Hg to 18.6 mm Hg with the gradient further declining at the 3-month follow-up. The NYHA classification also improved, with all patients categorized as either NYHA Class l or II. A total of 11 (9.6%) patients required a permanent pacemaker due to trifascicular block and 2 patients (1.8%) died during the hospital stay. Kuhn and colleagues reported on a case series of 215 procedures in 187 patients. (5) The perioperative mortality rate was 2.3%. At a mean follow-up of 2.4 years, the NYHA classification had decreased from 3.0 to 1.6. Similar to the data reported by Seggewiss, there were significant improvements in cardiodynamic measures, including outflow gradient and septal thickness. Gietzen and colleagues reported on 62 patients undergoing TASH, all of whom had substantial clinical improvement. The procedure-related early mortality was 4%, and a permanent pacemaker was required in 40% of patients. (6) Lakkis and colleagues reported on the 1-year follow-up of 50 patients undergoing TASH. (7) A total of 16% of patients required permanent pacemaker implantation. There were 2 perioperative deaths (4%). Prior to the procedure, all reported either NYHA Class III or IV symptoms compared to none at 1-year follow-up. Improvement in cardiodynamic assessments was consistent with the clinical improvements.

2003 Update Recent studies of TASH confirm earlier reported results. (8,9) One nonrandomized cohort study compared the outcomes of 51 patients who were treated with TASH (n=25) or myectomy (n=26). (8) Both treatment groups had reduced left ventricular outflow obstruction and significantly improved NYHA functional class immediately after treatment and at 3-month follow-up. However, reductions in pressure gradients were significantly lower in the myectomy group immediately after the procedure and during the 3-month follow-up than in the TASH group. Both groups had conduction system blocks (11 in TASH [9 with complete right bundle branch block and 2 with complete left bundle branch block] and 16 in myectomy [all had complete left bundle branch block]). Of those with conduction system blocks, 6 TASH patients required permanent pacemakers versus 2 patients in the myectomy group. Gietzen and colleagues reported that129 patients receiving TASH had significant beneficial clinical and hemodynamic effects after a median follow-up of 7 months regardless of whether the patients’ pre-TASH obstruction was resting or provocable. (9)

In summary, the data suggest that TASH, similar to myotomy/myomectomy, is associated with marked symptomatic and cardiodynamic improvement. It is not clear, however, whether the minimally invasive nature of TASH is associated with a decreased perioperative mortality rate. In the larger studies reviewed here, in patients undergoing myotomy/myomectomy alone, the perioperative mortality rate appears to range between 0% and 3%, which appears to be similar to the perioperative mortality rate reported for TASH. TASH appears to be associated with a high risk of atrioventricular heart block necessitating permanent pacemaker implantation. While long-term outcomes of myotomy/myomectomy appear to be satisfactory, the long-term outcomes of TASH are not known. Shorter hospital stays may make TASH more desirable in older patients with comorbid conditions, however, there is concern regarding the arrhythmogenicity of the infarcted septum, particularly since patients with hypertrophic cardiomyopathy are at high risk for complex ventricular arrhythmias. In addition, TASH will only cause reduction of the septum and will not be sufficient to relieve the outflow tract obstruction if there is elongation of the anterior or posterior leaflet of the mitral valve.

Population Reference No. 1 Policy Statement

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Population Reference No. 2 Policy Statement

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Population Reference No. 1 Policy Statement

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Supplemental Information

Practice Guidelines and Position Statements

Medicare National Coverage

References

1. Mohr R, Schaff HV, Danielson GK et al. The outcome of surgical treatment of hypertrophic obstructive cardiomyopathy. Experience over 15 years. J Thorac Cardiovasc Surg 1989; 97(5):666-74.

2. Robbins RC, Stinson EB. Long-term results of left ventricular myotomy and myectomy for obstructive hypertrophic cardiomyopathy. J Thorac Cardiovasc Surg 1996; 11(3):586-94.

3. Brunner-La Schonbeck HM, Rocca HP, Vogt PR et al. Long-term follow-up in hypertrophic obstructive cardiomyopathy after septal myectomy. Ann Thorac Surg 1998; 65(5):1207-14.

4. Seggewiss H, Faber L, Gleichmann U. Percutaneous transluminal septal ablation in hypertrophic obstructive cardiomyopathy. Thorac Cardiovasc Surg 1999; 47(2):94-100.

5. Kuhn H, Gietzen FH, Leuner C et aI. Transcoronary ablation of septal hypertrophy (TASH): a new treatment option for hypertrophic obstructive cardiomyopathy. Z Kardiol 2000; 89(suppl 4):IV41-54.

6. Gietzen FH, Leuner CJ, Raute-Kreinsen U et al. Acute and long-term results after transcoronary ablation of septal hypertrophy (TASH). Catheter interventional treatment for hypertrophic obstructive cardiomyopathy. Eur Heart J 1999; 20(18):1342-54.

7. Lakkis NM, Nagueh SF, Dunn JK et al. Nonsurgical septal reduction therapy for hypertrophic obstructive cardiomyopathy: one-year follow-up. J Am Coll Cardiol 2000; 36(3):852-5.

8. Qin JX, Shiota T, Lever HM et al. Outcome of patients with hypertrophic obstructive cardiomyopathy after percutaneous transluminal septal myocardial ablation and septal myectomy surgery. J Am Coll Cardiol 2001 Dec; 38(7):1994-2000.

9. Gietzen FH, Leuner CJ, Obergassel L et al. Role of transcoronary ablation of septal hypertrophy in patients with hypertrophic cardiomyopathy, New York Heart Association functional class III or IV, and outflow obstruction only under provocable conditions. Circulation 2002; 106(4):454-9.

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