Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy

JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY

VOL. 70, NO. 4, 2017

ª 2017 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION

ISSN 0735-1097/$36.00

PUBLISHED BY ELSEVIER

http://dx.doi.org/10.1016/j.jacc.2017.02.080

THE PRESENT AND FUTURE REVIEW TOPIC OF THE WEEK: POINT

Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy A Word of Endorsement Max Liebregts, MD,a Pieter A. Vriesendorp, MD, PHD,b Jurrien M. ten Berg, MD, PHDa

ABSTRACT 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. (J Am Coll Cardiol 2017;70:481–8) © 2017 by the American College of Cardiology Foundation.

H

ypertrophic cardiomyopathy (HCM) is the

HCM (6). Starting from 1960, Morrow used a tech-

most common inheritable cardiac disease,

nique in which a small, rectangular bar of muscle

present in 1 in 500 of the general popula-

from just below the aortic valve to beyond the site of

tion (1). Approximately two-thirds of patients with

mitral-septal contact was resected. The results of the

HCM have a significant gradient across the left

first 83 patients treated with this “Morrow procedure”

ventricular outflow tract (LVOT) at rest or during

were published in 1975 (7). Since then, numerous

physiological provocation and are classified as having

different surgical techniques have come and gone.

obstructive HCM (2). First-line treatment in patients

The objective of most of these procedures was

with significant LVOT obstruction is with negative

enlargement of the LVOT by means of myectomy to

inotropic

eliminate the systolic anterior motion of the anterior

drugs

(beta-blockers,

verapamil,

and

disopyramide) (3,4). In the 5% to 10% of patients

mitral valve leaflet and thereby reduce outflow

who remain highly symptomatic despite optimal

obstruction. Mitral valve plication, extension, and

medical therapy, septal reduction therapy is indi-

replacement have also been proposed as alternatives

cated, either by surgical myectomy or alcohol septal

to myectomy, and performed in selected patients

ablation (ASA) (3–5).

(8,9).

HISTORY OF SEPTAL REDUCTION THERAPY

to septal reduction began to take shape. Brugada et al.

At the end of the 1980s, an interventional approach (10) were the first to treat a patient by injecting Listen to this manuscript’s

First performed by Cleland in 1958, surgical myec-

absolute alcohol into a septal branch of the left

audio summary by

tomy was the first invasive treatment for obstructive

anterior descending artery. Their goal was not to treat

JACC Editor-in-Chief Dr. Valentin Fuster.

From the aDepartment of Cardiology, St. Antonius Hospital Nieuwegein, Nieuwegein, the Netherlands; and the bDepartment of Cardiology, Thorax Center, Erasmus Medical Center, Rotterdam, the Netherlands. The authors have reported that they have no relationships relevant to the contents of this paper to disclose. Manuscript received February 1, 2017; accepted February 7, 2017.

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Alcohol Septal Ablation for Obstructive HCM

ABBREVIATIONS

LVOT obstruction, however, but chemical

In 2010, ten Cate et al. (17) conducted the first of

AND ACRONYMS

ablation of ventricular tachycardia. The idea

the 6 studies comparing long-term outcomes of ASA

of reducing LVOT obstruction by a catheter-

and myectomy head to head. This study (subtitled “A

based method stems from the observation

Word of Caution”) is the only study to date that

that myocardial function of selected areas of

reported a worse outcome following ASA compared

the left ventricle can be suppressed by

with myectomy and is therefore frequently used

balloon occlusion of the supplying coronary

(>100 citations) by opponents of ASA. Two years

artery during angioplasty (11). In the years

later, Sorajja et al. (18), from the Mayo Clinic in

echocardiography

following the chemical ablation procedure

Rochester, Minnesota, compared ASA with myectomy

NYHA = New York Heart

reported by Brugada et al. (10), 2 groups of

by matching patients in a 1:1 fashion. The survival of

Association

researchers almost simultaneously devel-

ASA-treated patients was found to be comparable to

oped ASA for the treatment of obstructive HCM.

the age-and sex-matched general population and to

Gietzen et al. (12) presented their preliminary findings

age- and sex-matched myectomy-treated patients.

at the Annual Congress of the German Cardiac Society

Steggerda et al. (19) compared ASA-treated patients

in April 1994, and Sigwart presented his results at the

with myectomy-treated patients, focusing on peri-

Royal Brompton Hospital in London in June 1994 and

procedural complications and clinical efficacy. The

subsequently published the first 3 cases in The Lancet

same patients were also included in the largest study

(13).

of its kind, by Vriesendorp et al. (20), which included

ASA = alcohol septal ablation HCM = hypertrophic cardiomyopathy

LVOT = left ventricular outflow tract

MCE = myocardial contrast

NEEDLE VERSUS KNIFE Since its introduction, there has been a polarizing debate concerning the role of ASA in the management of obstructive HCM. Publications from the “surgical side” of the discussion are characterized by recycling of selected (early) outcomes of ASA, whereas the “interventional side” frequently disregards the limitations of ASA. Ideally, a randomized controlled trial should be set up to end the discussion about which procedure is best. This would require 1,200 patients eligible and willing to be randomized to a percutaneous or surgical procedure. Because the prevalence of HCM is 1 in 500 and <10% of these patients require septal reduction therapy, such a trial is practically impossible, as Olivotto et al. (14) clearly demon-

1,047 patients with HCM. During a mean follow-up of 7.6 years, survival after ASA or myectomy was found to be similar and comparable to that of patients with nonobstructive HCM. Finally, Samardhi et al. (21) and Sedehi et al. (22) described outcomes of relatively small groups of patients after ASA and compared these with outcomes following myectomy. Of the 50 studies found by the systematic review (16), 24 studies were selected for meta-analysis, containing 16 myectomy cohorts (n ¼ 2,791; mean follow-up 7.4 years) and 11 ASA cohorts (n ¼ 2,013; mean follow-up 6.2 years). When we repeated the same search for studies published from 2015 to 2016, we only found 1 additional study, by Yang et al. (23), comparing long-term outcomes following the 2 procedures (Table 1).

strated. Hence the only way to compare the 2 tech-

LONG-TERM OUTCOMES. The initial performance of

niques at this time is by retrospective analyses.

ASA was shrouded in safety concerns because of the

STUDIES COMPARING ASA WITH SURGICAL MYECTOMY.

intracoronary

ASA had to come of age, and the first substantial

creating a potentially arrhythmogenic ablation scar.

comparison with surgical myectomy was reported in

However, all but 1 of the aforementioned studies

2010 by Agarwal et al. (15). In this meta-analysis, 12

showed similar mortality rates after ASA and myec-

studies comparing techniques were included. The

tomy despite the more advanced age of most of the

most important limitation of this analysis was the

ASA cohorts (Table 1) (15,16,18–23). Annual sudden

short follow-up duration of the included studies

cardiac death rates (including appropriate implant-

(longest median follow-up 2.2 years), thus prohibiting

able cardioverter-defibrillator discharge) following

the investigators from making statements on long-

ASA were also found to be similar to those in post-

term outcomes. The meta-analysis we performed in

myectomy patients, ranging from 0.4% to 1.3%,

2015 therefore only included studies with a follow-up

when

of at least 3 years (16). Remarkably, only 6 studies

(16,18,20,21).

injection

including

of

unknown

cardiotoxic

deaths

ethanol,

(Table

1)

comparing ASA with myectomy were identified

The primary endpoint of the study by ten Cate

(Table 1) (17–22). In contrast, 44 studies were found

et al. (17) was an unusual composite of cardiac death,

describing the outcomes of 1 of the 2 interventions

aborted sudden cardiac death, and appropriate

(16), a finding that may also be seen as a sign of the

implantable

ongoing polarization.

without

cardioverter-defibrillator

discriminating

between

discharge,

periprocedural

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483

Alcohol Septal Ablation for Obstructive HCM

T A B L E 1 Outcomes of All Studies Comparing ASA With SM With a Mean Follow-Up Duration of at Least 3 Yrs and Results of Meta-Analyses Comparing

ASA With Myectomy

Period

n

Mean Follow-Up, yrs

Agarwal, 2010 (15)

6 countries

1986–2006

380/326

—

55/49*

ten Cate, 2010 (17)

the Netherlands

1999–2007

91/40

5.4/6.6

54/49

2.2/0‡

5.5/0‡

4/3

Sorajja, 2012 (18)

United States, Rochester

1983–2010

177/177

5.7/5.7

63/62

1.1/0.6

1.7/0.6

Steggerda, 2014 (19)

the Netherlands†

1981–2010

161/102

5.1/9.1

59/56

1.2/2.0

2.5/0

Vriesendorp, 2014 (20)

Belgium and 1990–2012 the Netherlands†

316/250

6.3/7.9

58/52*

1.6/1.2

3.1/0.4*

Samardhi, 2014 (21)

Australia

1981–2012

47/23

3.6/3.8

57/47*

0/8.7

Sedehi, 2015 (22)

United States, Stanford

1972–2006

52/171

3.2/13.7

57/48‡

0/2.9‡

Liebregts, 2015 (16)

16 countries

1963–2013

2,013/2,791

6.2/7.4

56/47*

Yang, 2015 (23)

China

2001–2014

22/37

3.0/3.0

46/45

First Author, Year (Ref. #)

Country

Mean Age, yrs

Peri Mortality, %

Peri (A)SCD, %

NS

NS

Pacemaker, %

Mean LVOTG, mm Hg

All-Cause (A)SCD REDO, Mortality (Annual), % (Annual), % %

NS

—

—

8/–

11/5‡

1.8/0.8§

—

22/4

13/–*

9/1*

2.5/2.4

1.3/1.1k

7/9

19/10*

6/1*

1.5/2.2

—

—

10/9*

10/2*

1.9/2.0

1.0/0.8k

4.3/0

15/13

27/13

17/0*

1.2/4.6

0/0

—

8/6‡

36/34‡

—

1.2/1.0

—

1.3/1.1§

2.2/0.6§

10/4*§

—

8/2*

1.5/1.4

0/0

4.5/2.7‡

0/0

—

5/0‡

1.5/0.9

OR: 2.6 SMD 0.45 (favors SM) (favors SM)

0.4/0.5 0/0.9§

Values are ASA-treated patients/SM-treated patients. *p < 0.05. †Patients also included in other study. ‡No statistical comparison conducted. §Studies from before the year 2000 were excluded. kIncluding death from unknown cause. Studies in bold are meta-analyses comparing ASA with myectomy. ASA ¼ alcohol septal ablation; (A)SCD ¼ (aborted) sudden cardiac death, including appropriate implantable cardioverter-defibrillator discharge; LVOTG ¼ post-procedural (provocable) left ventricular outflow tract gradient; OR ¼ odds ratio; Peri ¼ periprocedural (<30 days); REDO ¼ reintervention during follow-up (either ASA or SM); SM ¼ surgical myectomy; SMD ¼ standardized mean difference.

events and late events. Patients undergoing ASA had

borderline significance (p ¼ 0.055). Thus, there are

a 5-fold increase in the estimated annual primary

reasons to believe that there is a slightly higher risk of

endpoint rate compared with those undergoing

periprocedural

myectomy (4.4% vs. 0.9%). When we calculated this

ASA. This also makes sense from a pathophysiological

composite endpoint for the different ASA cohorts

point of view because of the increased arrhythmoge-

included in the 2015 meta-analysis (16), one-half of

neity of an acute myocardial infarction. However, as

them had estimated rates <0.9%/year, and only 3

shown

cohorts were found to have an annual rate >1.5%

procedural care prevent increased 30-day mortality

(Lyne et al. [24], 1.8%; Veselka et al. [25], 1,8%; and

rates.

Vriesendorp et al. [20], 1.9%).

ventricular

before,

good

arrhythmias

periprocedural

following

and

post-

The need for pacemaker implantation following

PERIPROCEDURAL COMPLICATIONS AND TREATMENT

both procedures varies considerably among the

EFFECT. None of the studies discussed in the pre-

studies discussed earlier (0% to 22% following ASA,

ceding text found a difference in 30-day mortality

compared with 0% to 13% following myectomy)

rates between the 2 procedures (15,18–21,23), except

(Table 1). In their meta-analysis, Agarwal et al. (15)

for the 2015 meta-analysis, which showed a peri-

found an increased risk of permanent pacemaker

procedural mortality rate following myectomy twice

implantation following ASA, with an odds ratio of

as high compared with ASA (16). However, in light of

2.6. This finding is identical to the 10% pacemaker

the potentially less-developed periprocedural care in

implantations following ASA, compared with 4%

the 20th century, when studies from before 2000

pacemaker implantations following myectomy, that

were excluded, the periprocedural mortality rates of

was found in the 2015 meta-analysis (16).

both procedures were close to equal. The only study that found a higher rate of peri-

The meta-analysis by Agarwal already showed a slightly higher LVOT gradient after ASA compared

procedural ventricular arrhythmias following ASA

with myectomy (15). However, no significant differ-

was by Vriesendorp et al. (20). The 2015 meta-analysis

ences were found in the reintervention rate. It took

showed a similar incidence of periprocedural ven-

studies with long-term follow-up to discover a higher

tricular arrhythmias following both procedures (16).

need for reinterventions following ASA compared

However, when studies from before 2000 were again

with myectomy (18–21). The observation of a slightly

excluded, the periprocedural event rate became 2.2%

higher LVOT gradient after ASA compared with

after ASA compared with 0.6% after myectomy, with

myectomy

was

confirmed

by

the

3

largest

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Alcohol Septal Ablation for Obstructive HCM

PATIENT SELECTION AND SPECIALIZED CARE. The

F I G U R E 1 Decision Tree for Patients With Obstructive HCM and

2011 American College of Cardiology Foundation/

Complicating Patient Factors

American Heart Association guidelines state that surgical myectomy is the gold standard for patients Adult patient with medical therapy resistant obstructive HCM

with medical therapy–resistant obstructive HCM, and that ASA should be reserved for older patients or patients with serious comorbidities (3). Despite these recommendations, recent figures show that w43% of

Surgical necessity? • Mitral valve pathology • Three-vessel disease • Mid-cavity obstruction by papillary muscles

YES

F I T

NO

U.S. patients undergo ASA instead of myectomy (26),

• MitraClip (± ASA) • PCI + ASA • Conservative treatment

and these numbers are known to be even higher in Europe (27). This is another reason why we should spend less time discussing which procedure is best and more time discussing how to select the right

NO NO

Presence of suitable perforator for ASA?

F O R

patient for the right procedure. YES

YES S U R G E R Y

Pro myectomy • Less suitable septal anatomy for ASA • Pre-existent LBBB Pro ASA • Moderate AVI • Pre-existent RBBB • (Pre-existent CHB)

YES

Most of the studies discussed previously were Surgical myectomy

conducted in high-volume centers. The correspond-

± Valve surgery ± CABG

patients are referred to such centers. This is in

ing figures are therefore applicable only when accordance with the guidelines, which state that only experienced operators with cumulative case volumes of at least 20 procedures should perform myectomies

Patient preference

(United States) or that a minimal caseload of 10 ASA NO

Alcohol septal ablation

or myectomies is required (Europe) (3,4). A recent study on hospital volume outcomes after septal reduction therapy in U.S. hospitals showed that 60% of the centers had performed <10 myectomies during the 9-year study period, whereas 4 institutions had

Decision tree that can be used by the multidisciplinary heart team for

performed 36% of all the isolated myectomies during

patients with obstructive hypertrophic cardiomyopathy (HCM) and

the same time period. This finding is of particular

complicating patient factors. ASA ¼ alcohol septal ablation; AVI ¼ aortic valve insufficiency; CABG ¼ coronary artery bypass grafting;

concern because the low-volume centers were found

CHB ¼ complete heart block; LBBB ¼ left bundle branch block;

to have 3-fold higher in-hospital mortality rates

PCI ¼ percutaneous coronary intervention; RBBB ¼ right bundle

(15.6%) compared with high-volume centers. The

branch block.

same was found for ASA, with 67% of the centers having performed <10 procedures during the study period. However, undergoing ASA in low-volume centers was not associated with worse outcome

aforementioned outcome studies (Table 1) (18–20).

(in-hospital mortality 2.3%) when compared with

According to the 2015 meta-analysis, myectomy was

high-volume centers. This finding could be a reflec-

not significantly more effective in reducing the LVOT

tion of a significantly steeper learning curve associ-

gradient at long-term follow-up. We think, however,

ated with myectomy and the relative ease with which

that the need for reintervention is the best clinical

operators with experience in catheter-based therapy

parameter for determining the overall efficacy of the

adapt ASA (26). These findings do not mean that ASA

procedures. In the 2015 meta-analysis, the incidence

can be conducted everywhere, whereas myectomy

of additional sepal reduction therapy was 7.7%

needs to be confined to a few centers. All care for

following ASA compared with 1.6% following myec-

patients with HCM who require septal reduction

tomy. Despite (or because of) these reinterventions,

therapy should be confined to HCM centers of excel-

none of the aforementioned studies found a differ-

lence where both procedures are available and are

ence in New York Heart Association (NYHA) func-

used in a complementary and not competing manner.

2

The decision to perform myectomy or ASA is not

procedures (15,16,18–23). Moreover, when patients

solely based on the outcomes described previously.

were asked explicitly by means of a questionnaire at

Similar to patients undergoing surgical or catheter-

late follow-up in the study by Steggerda et al. (19), no

based aortic valve replacement (28), all patients un-

differences in functional status were found between

dergoing septal reduction therapy should be dis-

ASA-treated and myectomy-treated patients.

cussed in a multidisciplinary heart team consisting of

tional

class

at

late

follow-up

between

the

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Alcohol Septal Ablation for Obstructive HCM

C ENTR AL I LL U STRA T I O N Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy: Key Messages

Liebregts, M. et al. J Am Coll Cardiol. 2017;70(4):481–8.

Schematic depiction of the alcohol septal ablation (ASA) procedure and key messages on outcomes following alcohol septal ablation to help facilitate shared decision making. AED ¼ automated external defibrillator.

an imaging cardiologist, an interventional cardiolo-

leaflet). In contrast, a high operative risk because of

gist experienced with ASA, and a surgeon experi-

advanced age and/or comorbidities will frequently

enced with myectomy (3,4). Here, additional patient-

result in the choice for ASA. Sometimes ASA is not

related factors can be taken into account. For

possible because of the absence of a suitable septal

example, the need for concomitant valve surgery or

perforator. Finally, existing conduction disturbances

coronary artery bypass grafting will, in most cases,

can play a part in making the decision. Because ASA

make myectomy the better choice, as will midcavity

frequently causes a right bundle branch block, a

obstruction by papillary muscles requiring surgical

pre-existing left bundle branch block could make

correction

muscles,

myectomy the preferable option. Conversely, because

accessory papillary muscles, direct insertion of ante-

myectomy frequently creates a left bundle branch

rolateral papillary muscle into the anterior mitral

block, a pre-existing right bundle branch block could

(i.e.,

hypertrophic

papillary

485

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Alcohol Septal Ablation for Obstructive HCM

Through shared decision making, each individual

F I G U R E 2 Relationships Among Alcohol Volume, LVOT Gradient Reduction, and

patient can weigh these higher risks following

Incidence of Periprocedural Complete Heart Block

ASA against the somewhat higher burden of (rehabilitation after) open heart surgery and make a measured 100

decision. *Periprocedural Complete Heart Block (%)

LVOT Gradient Reduction (%)

90 80 70 60 50

44 *

40 30

32 *

43 *

35 *

34 *

20

IMPROVING OUTCOMES OF ASA TECHNICAL ADVANCES. In the early days of ASA,

relatively high volumes of alcohol were used. For example, the first 3 cases described by Sigwart (13) were treated with an average of 4.5 ml. The most frequently heard critique on the study by ten Cate et al. (17) was the use of high volumes of alcohol in its ASAtreated patients (mean 3.5 ml, compared with a median of 2.5 ml in the 2015 meta-analysis). However, in their analysis, no effect of alcohol dosage on their

10

primary endpoint was observed. Over time, clinical experience, combined with better strategies to iden-

0 0.4-1.4

1.5-1.9

2.5-2.9

2-2.4

tify the target septal branches, has led to the use of

3-11

lower volumes of alcohol during ASA (29,30).

Alcohol (mL)

Initially, selection of the appropriate septal perfo-

LVOT gradient reduction (%) no improvement 70-79

<50

50-59

80-89

rator was made on the basis of an immediate decrease

60-69

of the LVOT gradient following balloon occlusion. In

90-100

1998, myocardial contrast echocardiography (MCE) The European alcohol septal ablation (Euro-ASA) registry (n ¼ 1,275) was conducted to

was introduced (31,32). With the use of MCE, the

identify predictors of outcome following alcohol septal ablation. The volume of alcohol

perfusion area of a septal branch can be shown on

used for ASA was found to be associated with left ventricular outflow tract (LVOT)

echocardiography

reduction and incidence of periprocedural complete heart block. On the basis of these

graphic contrast medium. The use of this technique

findings, ASA alcohol volumes ranging between 1.5 and 2.5 ml were deemed well

after

injection

of

echocardio-

has proved to be a useful influence on interventional

balanced in terms of efficacy and safety for most patients. Adapted from Veselka J, Jensen MK, Liebregts M, et al. Long-term clinical outcome after alcohol septal ablation

strategy in 15% to 20% of cases, by either changing

for obstructive hypertrophic cardiomyopathy: results from the Euro-ASA registry. Eur

the target vessel or prompting the procedure to be

Heart J 2016;37:1517–23, by permission of the European Society of Cardiology.

aborted when remote parts of the myocardium light up. In addition, it has improved the success rate of ASA, despite lower infarct sizes (33,34). The latest

be an argument for ASA. An implanted pacemaker for

innovation in ASA is 3-dimensional MCE-guided ASA.

a pre-existing complete heart block could also play a

With added accuracy and the ability to quantify the

role in decision making for obvious reasons. Figure 1

expected size of myocardial tissue affected by the

depicts

by

ablation, this new technique has the potential to

the multidisciplinary heart team for patients with

further improve the safety and effectivity of ASA (35).

medical

However, substantial outcome studies on the use of

a

decision

tree

therapy–resistant

that

can

be

obstructive

used HCM

and

complicating patient-related factors. When an adult patient has no complicating factors,

3-dimensional MCE guided ASA have yet to be conducted.

we can state that, on the basis of the aforementioned

The introduction of percutaneous mitral valve

results, ASA and myectomy appear to be equally

plication with use of the MitraClip (Abbott Vascular,

safe. However, patients undergoing ASA have a 1 in

Santa Clara, California) has brought an interventional

10 chance of permanent pacemaker implantation,

alternative to ASA for the treatment of obstructive

whereas that risk is 1 in 25 after myectomy (15,16).

HCM. To date, only 2 small studies have been con-

Furthermore, there is a 1 in 13 chance that ASA-treated

ducted, but initial results are promising (36,37).

patients will have to undergo reintervention, either by

Additional studies with long-term follow-up will be

repeat ASA or by myectomy, which is 5 times the risk

necessary to determine the role of this technique in

of a repeat procedure following myectomy. Nonethe-

the treatment of patients with obstructive HCM and

less, symptom relief at long-term follow-up is similar

increased operative risk. One of the main questions

after both procedures (Central Illustration) (16).

will

be

whether

the

technique

should

be

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Alcohol Septal Ablation for Obstructive HCM

complementary to ASA or whether the MitraClip can

gradient was found to be of particular importance

serve as an independent alternative.

because it was an independent predictor of survival

PREDICTORS OF OUTCOME. Recently, 2 large regis-

and symptom relief at last follow-up. However, a

tries were established to identify predictors of

(transient)

outcome following ASA. The North American Registry

resulted in permanent pacemaker implantation in

included 875 patients who underwent ASA at 9 in-

one-third of patients (12% of all patients). On the

periprocedural

complete

heart

block

stitutions in the United States and Canada and were

basis of these findings, ASA alcohol volumes ranging

followed up during a mean of 2.1 years (38). Survival

between 1.5 and 2.5 ml were deemed well balanced in

estimates at 1, 5, and 9 years were 97%, 86%, and

terms of efficacy and safety for most patients (Central

74%, respectively. Baseline predictors of mortality

Illustration).

were a higher NYHA functional class and a lower

CONCLUSIONS

ejection fraction. Post-procedural predictors were all concordant in showing that a more effective ablation

Twenty years after the introduction of ASA for the

was associated with a lower likelihood of death

treatment of obstructive HCM, the arrhythmogenicity

(smaller septal thickness 3 months post-ablation, not

of the ablation scar appears to be overemphasized.

taking beta-blockers post-ablation, and absence of

When systematically reviewing all studies comparing

the need for repeat procedures). Of note is that a

ASA with myectomy with long-term follow-up,

relationship between failed myectomy and death has

(aborted) sudden cardiac death and mortality rates

also been reported before (39).

were found to be similarly low. Instead, the focus

The European ASA (Euro-ASA) registry included

should be shifted toward how to lower the rate

1,275 patients who underwent ASA at 10 tertiary

of reinterventions and pacemaker implantations

centers

were

following ASA because ASA still seems to be inferior

followed-up during a median of 5.7 years (40). The

to myectomy in this regard. Part of the reason for this

30-day mortality rate was 1%, which is similar to the

difference is that ASA is limited by the route of the

rates following ASA and myectomy in the 2015 meta-

septal

analysis (16). Survival estimates at 1, 5, and 10 years

Improvement in this area may be achieved, however,

from

7

European

countries

and

perforators,

whereas

myectomy

is

not.

were 98%, 89%, and 77%, respectively. Remarkably,

by: 1) confining ASA to HCM centers of excellence

this means that the 10-year survival rates of the

with high operator volumes; 2) improving patient

largest ASA and largest myectomy cohort to date are

selection by means of multidisciplinary heart teams;

identical (Schaff et al. [41] reported a 10-year survival

3) the use of (3-dimensional) MCE for selecting the

rate of 77% in 749 patients operated on at the Mayo

correct septal (sub)branch; and 4) the use of appro-

Clinic in Rochester, Minnesota). Baseline predictors

priate amounts of alcohol for ASA.

of mortality were higher age, NYHA functional class, and septal thickness. The volume of alcohol used for

ADDRESS

ASA was found to be a predictor of LVOT reduction

Liebregts, Department of Cardiology, St. Antonius

FOR

CORRESPONDENCE:

and was associated with a higher incidence of com-

Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, the

plete heart block (Figure 2). Reduction of the LVOT

Netherlands. E-mail: [email protected].

Dr.

Max

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KEY WORDS heart team, patient selection, septal reduction therapy, sudden cardiac death, treatment outcome