Resistant Obstructive Hypertrophic Cardiomyopathy: Myomectomy or Septal Ablation?

Approximately 70% of hypertrophic cardiomyopathies (HCM) are associated to a left ventricular outflow tract (LVOT) obstruction and mitral valve failure leading to dyspnea and cardiac failure in a high number of patients.

Miocardiopatía obstructiva hipertrófica refractaria ¿miomectomía o ablación septal?

Even though at present there are effective drug treatments combined with pacemaker implantation, surgery (septal myomectomy (SM) continues to be the first choice of treatment for restrictive HCM, with close to 6% mortality (3.8% in high volume centers and 13.8% in low volume centers).

A strategy that has seen great advance is alcohol septal ablation (ASA), which presents 0.6% mortality in high volume and 2.3% in low volume centers.

Different studies on SM and ASA have shown that transcatheter intervention is safe and effective, yet long term data remains to be clarified.

The study looked at 5679 Medicare patients older than 65 undergoing septal ablation for obstructive HCM. 3680 of these patients (64.80%) received SM and 1999 ASA.

Patients undergoing SM were younger (72.9 vs. 74.8 p=0.001), more often women, with less hypertension, diabetes, anemia, cardiac failure, cerebrovascular disease, pulmonary hypertension, kidney or liver failure, and frailty. They also presented fewer hospitalizations for cardiac failure the previous year.

SM was associated to higher hospital mortality (4.5% vs 1.5% P < 0.001), stroke (3.0% vs <0.6% P < 0.001), new kidney function deterioration requiring dialysis (2.2% vs <0.6% p<0.001), and higher mortality at 30 days (5.1% vs 2.0% P < 0.001).

Mean followup was 4 years, with no difference in mortality (HR: 0.87; 95% CI: 0.74-1.03 P= 0.1). The first two years there were no differences in mortality rate (HR: 1.11; 95% CI: 0.88-1.40; P = 0.40), but the third and fourth years showed lower morality with SM (HR: 0.72; 95% CI: 0.60-0.87; P < 0.001).

Reintervention was lower with SM (HR: 0.10; 95% CI: 0.07-0.15; P < 0.001) and both strategies reduced hospitalization for cardiac failure vs. prior year with no difference between procedures.

High volume centers presented worse outcomes vs. low volume centers. However, 70% of patients were treated at low volume centers.

Conclusion

Septal reduction therapy lowers readmission for cardiac failure in Medicare patients with obstructive HCM. Septal reduction surgery was associated to lower reintervention rate and longer survival compared against septal ablation. Even though high-volume centers presented better outcomes, 70% of septal reduction treatments are carried out in low volume centers.