Importance of genetic testing in unexplained cardiac arrest

It is known that nearly 70% of the patients diagnosed with hypertrophic cardiomyopathy demonstrate dynamic left ventricular outflow tract obstruction resulting in symptomatic heart failure, syncope and reduced exercise capacity. Although age at presentation can vary, it has increasing over time, with higher representation of elderly patients nowadays. In fact, mean age of the patients included in the new trials with mavacamten such as EXPLORER-HCM and VALOR-HCM were around 60 years old. This change in demographic profile reflects the greater visibility and recognition of HCM, and should prompt new recommendations regarding which could be the most suitable therapeutic option for each individual.

In the present article, authors studied long-term outcomes of septal reduction therapies in Medicare patients with obstructive hypertrophic  cardiomyopathy (HOCM) older than 65 years old. They include a total of 5679 patients who underwent septal myectomy (SM= 3680) or alcohol septal ablation (ASA=1999) from 2013-2019. Patients treated with SM were younger and more frequently men ( 72.9 vs 74.8 years old, women 67.2% vs 71.1% p<0.01).  Consistent with prior studies SM was associated with higher mortality and morbidity compared with ASA in the short terms (frailty and older age in ASA group), better long-term survival and significantly lower need for reoperation.

Higher complications were described up to three months following SM vs ASA, but on the contrary SM was associated with lower mortality after two years of follow-up (HR: 0.72; 95% CI: 0.60-0.87 P<0.001) and lower need for redo SRT. Both treatments reduced HF readmissions.

Despite better outcomes in high volume centers, 70% of the treatments were performed in low volume US centers despite guideline recommendations and presenting worse outcomes.

Then, and although both therapies are safe and with reasonable short and long term outcomes, the decision to pursue any of the options should  be based on patient’s decision and on heart team’s discussion. 

This is again the longstanding debate between SM and ASA. The decision should be made taking into account possible comorbidities , LVOT anatomy, mitral valve disease but also local expertise in both procedures. SM  is safe and provides a permanent relief, being able to address also different phenotypic expressions such as mild or extreme degrees or more apical hypertrophy as well as associated valvular or subvalvular abnormalities. On the other hand, ASA is less invasive with shorter recovery period, but presents a higher risk of AV block and of suboptimal reduction of the gradient. This outcomes had relegate until now this technique to those patient with serious comorbidities or  of advanced age. In view of the results of the present article maybe is time to evaluate surgery also in older patients.