Hypertrophic Cardiomyopathy—One Case per Year? A Clarion Call to Do What Is Right

Hypertrophic cardiomyopathy (HCM) has fascinated (and scared) cardiologists for years owing, in part, to the relatively fewcasesmostphysicianswill see intheirpractice,coupledwith increased risk for sudden death, complex yet incomplete genetic understanding, and enigmatic hemodynamics. The management of symptomatic patients with HCM evolved over the past (nearly) 6 decades owing to focusedefforts tounderstandthepathophysiologyandperfect the necessary skills to delivery exemplary outcomes.1 We have learned that it is entirelypossible forpatientswithHCMtohave excellent quality of life and normal lifespans, that most patients can be treatedwith pharmacologic therapy, and that for most patients who remain symptomatic, there are procedures that can deliver excellent benefit with low risk. The article by Kim et al2 using a national discharge database samplingmethod examines observed event rates among patients undergoing surgical septal myectomy or percutaneous septal ablation. Some of the findings are not surprising: there is a clear association between procedural volume and complications and there aredifferences in baseline characteristicsbetweenpatientsundergoing the2procedures.Thereare someshocking results: themediannumberofmyectomycases or ablation cases in this database is less than or equal to 1 case per year. Seriously, only 1 case per year? Why would we subject our patients to this? There is somecritical informationmissing as an artifact of the study design: specifically, there are no effectiveness data and thus, a comparison cannot be made between the results of surgical septal myectomy vs septal ablation. More importantly, there is no description of what can be expected if the procedures were performed not just at higher volume centers, but at Centers of Excellence. The study of Kim et al2 in this issue of JAMA Cardiology does go a long way to making an excellent case for having a few highly focused centers that specialize in the care of patients with HCM. The results achievable at major HCM centers are remarkable. In expert hands, surgical myectomy has a greater than 95% efficacy, with mortality rates that are approaching 0% (ie, thousands of cases performed without an operative death), normalization of long-term survival following theprocedure, anda reduction in sudden cardiacdeath.3-5 Similarly, among those patients who respond to septal ablation, the symptomatic improvement canmirror that ofmyectomy, with a procedural mortality rate that is only about 1%.6 Given that there are recognizable differences in complication rates and controversy regarding the association between septal ablation and subsequent sudden cardiac death/ implantable cardioverter defibrillator discharge rates, the American College of Cardiology Foundation/American Heart Association guidelines, as stated in the current article, recommendsurgicalmyectomyas thepreferredstrategy formostpatientswithHCMwith drug-refractory symptoms and that ablation isa reasonablealternative inselect cases.7Theguidelines emphasize that both procedures be performed by experienced centers and recommenda shareddecision-makingprocess, inwhich the fully informed patient is able to choose the procedure based on their own needs and preferences. Looking specifically at the data in the current report,2 regardless of the procedure type, there is an approximate 4-fold increase inmortality comparing the high-volume tertile to the low-volume tertile. Notably, the best mortality rates for myectomy as reported in this article, from their high-volume tertile, arestillnearly 10-foldhigher thanwhat is seenatHCMcenters.8 Thatevenhigher-volumecentersappear tohaveamortality rate that is 10 timesgreater thanwhat isobservedat centerswith focusedexpertise inHCMisanimportantobservationthat isworth seriousdiscussion. Indeed, thismayunderestimate themagnitude of the differences. Based on the data presented, the lowvolumecenterswould expect aprocedure-relateddeath for every 6 attempts, while the highest tertile reported here would expect a death for every 26 attempts. Yet,weknow frompreviouslypublisheddatathatHCMcenterscango1500ormorecases withoutaprocedure-relateddeath.8Sixvs26 is incremental improvement; 26 vs 1500 is improvement measured in magnitudes of order. There should be no debate. For years, the cardiology community has recommended andaccepted that adultswith congenital heart disease should receive their care from regional specialized centers for adults with congenital heart disease.9 Recently, given thewide variability in outcomes following operations for mitral valve disease, a disease and set of procedures that are far more prevalent than HCM, there has been a thoughtful call for these procedures to be restricted to those centers that can demonstrate excellence in benefit and safety.10 Hypertrophic cardiomyopathyhas a complexity andprevalence thatmore closely mimics that of adults with congenital heart disease, but HCM also has important abnormalities of mitral valve function. It is in the best interest of the patients then that they be informed they can expect to have a procedure with a vanishingmortality rateand95%chanceof significant,durable symptomatic benefit. No patient should have a complex procedure done where the volume is 1 per year. The data in this current report,2 coupledwith thewell-establisheddata fromHCMCenters of Excellence, make a clear case that for HCM, not every hospital or operator should be performing these procedures. The low-volume safety data are unacceptable. The middle volume data are not good enough. Even the highest-volume Editor's Note page 334