Surgical Treatment of HCM

Question 1

What is surgical myectomy?

Answer 1

Involves removing a portion of the hypertrophied septum that causes LVOTO

Question 2

Who receives myectomy?

Answer 2

Patients with drug refractory symptoms or elevated resting outflow gradients

Question 3

How successful is Myectomy?

Answer 3

Substantially reduces outflow gradients in >90% of cases and produces 70-80% long term benefit to symptoms

Question 4

What is Septal ablation?

Answer 4

Injected ethanol triggers necrosis to part of the hypertrophied muscle creating a localised scar that reduces septal obstruction of the LVOT
*Can also be performed using radio-frequency

Question 5

Surgical Myectomy or Septal Ablation?

Answer 5

Septal myectomy, rather than SAA, is recommended in patients with an indication for septal reduction therapy and other lesions requiring surgical intervention (e.g. mitral valve repair/replacement, papillary
muscle intervention).- Class 1 Level C evidence

Question 6

What is the evidence for myectomy over ablation?

Answer 6

Maron et al, 2012:
Myectomy shown to produce a greater reduction of outflow gradients that ablation
Myectomy mortality is 1%, ablation mortality is 2%
Ablation has a 15% risk of pacemaker necessity due to the induction of heart block, so ablation is recommended for older patients with co-morbidities that reduces the ability to undergo surgery *Ablation can be done with the patient awake
*There are no RCTs of surgical therapies

Question 7

HCM and Pacing:

Answer 7

Pre-exciting the RV causes LV apical activation prior to septal activation so excursion of the septal wall into the LVOT is reduced
And pacing is negatively inotropic so the ejection acceleration is reduced which decreases early forces on the mitral valve

Question 8

What do guidelines say about pacing?

Answer 8

Sequential AV pacing, with optimal AV interval to reduce the LV outflow tract gradient or to facilitate medical treatment with ß-blockers and/or verapamil, may be
considered in selected patients with resting or provocable LVOTO 50 mm Hg, sinus rhythm and drug-refractory symptoms, who have contraindications for septal alcohol ablation or septal myectomy or are at high risk of developing heart block following septal alcohol ablation or septal myectomy.-Class IIb level C

Question 9

Evidence for Septal reductio over Pacing:

Answer 9

Gao et al, 2007:
Compared pacing to ASA
Found that ASA was superior and pacing should only be offered to patients who are unable to or unwilling to opt for alternatives