NEW YORK CITY, NY — A retrospective study of more than 10,000 septal-reduction procedures for obstructive hypertrophic cardiomyopathy (HCM) shows a roughly fourfold increase in in-hospital death at low-volume hospitals compared with high, regardless of procedure type[1].
Equally disturbing, the median number of septal myectomy and alcohol septal ablation cases was just 1% and 0.7% per year, the investigators, led by Dr Luke K Kim (Weill Cornell Medical Center, New York, NY), reported online April 27, 2016 in JAMA Cardiology.
"This is a wake-up call to the cardiology community that we have to dedicate a lot more effort into sending these patients with very complex medical problems to centers of excellence, whether that's for septal myectomy or septal ablation. I think it applies to both," Kim told heartwire from Medscape.
The 2011 American College of Cardiology Foundation guidelines for HCM have been well publicized and are very clear that septal reduction by either procedure should be performed only by experienced surgeons at comprehensive HCM clinical programs, of which there are easily more than a dozen in the US that can handle these largely elective procedures, he said.
An accompanying editorial[2] by Drs Steve Ommen and Rick Nishimura (Mayo Clinic, Rochester, MN) describes the paltry number of cases performed each year as shocking. "Seriously, only one case per year? Why would we subject our patients to this?"
They contend the study "goes a long way to making an excellent case" for having centers with focused expertise in HCM, observing that even the high-volume centers appear to have a mortality rate for myectomy that's still nearly 10-fold higher than what's seen at HCM centers.
Based on the data, low-volume centers could expect a procedure-related death for every six attempts and high-volume centers a death for every 26 attempts. "Yet we know from previously published data that HCM centers can go 1500 or more cases without a procedure-related death. Six vs 26 is incremental improvement; 26 vs 1500 is improvement measured in magnitudes of order. There should be no debate," they add.
Drs Robert Bonow and Dr Clyde Yancy (Northwestern University, Chicago, IL) write in an editor's note[3] on the study that the data "point out the gulf between clinical-practice guidelines and practice."
In addition to the lack of guideline adherence, Kim said the data may also reflect patient preference, a lack of HCM centers in rural areas, and a comfort level among interventional cardiologists, particularly given the lower learning curve with septal ablation. Indeed, during the 9-year study period, the annual rate of septal myectomy decreased 24.5%, while the annual rate of septal ablation increased by 56.2%.
"I worry that this reflects myectomy cases that, rather than being referred out to centers of excellence, are being by done by interventionalist cardiologists performing septal ablation locally," he said.
Slight Procedural Differences
The study examined discharge records for 11,248 HCM patients in the National Inpatient Sample database from all hospitals that performed septal-reduction procedures from 2003 through 2011.
In-hospital mortality in the highest- and lowest-volume tertiles varied from 3.8% to 15.6% after septal myectomy (P<0.001) and from 0.6% to 2.3% after septal ablation (P=0.02).
The need for a permanent pacemaker and major bleeding were also higher at lowest-volume hospitals after myectomy, as was acute renal failure after ablation.
Multivariate adjustment attenuated the association between hospital volume of septal ablation and postprocedural adverse events, but undergoing myectomy in lowest-volume centers remained an independent predictor of in-hospital all-cause mortality (odds ratio [OR] 3.11) and major bleeding (OR 3.77).
"Even though there's slightly less difference between high- and low-volume centers for septal ablation, the procedure should still be performed at high-volume centers, especially because septal myectomy is still the preferred method over septal ablation in the guidelines," Kim said.
At baseline, patients undergoing septal ablation in lowest- vs highest-volume centers were older and more likely to have comorbidities including diabetes, anemia, chronic pulmonary disease, chronic renal failure, and liver disease.
The investigators are currently looking at the breakdown of patient characteristics to determine who was more likely to undergo septal myectomy and whether these characteristics changed over time.
Kim reported no relevant financial relationships. Disclosures for the coauthors are listed in the article. The editorialists and Bonow and Yancy reported no relevant financial relationships.
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Heartwire from Medscape © 2016 Medscape, LLC
Cite this: Red Flags for Low-Volume HCM Ablation, Myectomy Centers - Medscape - Apr 28, 2016.
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