ABSTRACT & COMMENTARY
By Michael H. Crawford, MD, Editor
SOURCES: Steggerda RC, et al. Periprocedural complications and long-term outcome after alcohol septal ablation versus surgical myectomy in hypertrophic obstructive cardiomyopathy: A single-center experience. JACC Cardiovasc Interv 2014;7(11):1227-1234;
Geske JB, et al. Myectomy versus alcohol septal ablation: Experience remains key. JACC Cardiovasc Interv 2014;7:1235-1236.
Symptomatic left ventricular outflow tract (LVOT) obstruction is common in patients with hypertrophic obstructive cardiomyopathy (HOCM), and medical therapy does not always relieve the symptoms. In such cases, septal reduction therapies are indicated, and both alcohol septal ablation (ASA) and surgical myectomy have been proven to reduce symptoms effectively. However, there is controversy concerning the post-procedure complications and long-term success of both procedures. Thus, these investigators from the Netherlands analyzed their single center experience from 1981 through 2009. ASA was introduced in 2000, and from then on, after a discussion of the potential risks and benefits of both procedures, patients were offered a choice of which they preferred. The primary endpoint was all-cause mortality during a maximum follow-up of 11 years for both procedures. Several secondary clinical endpoints were also assessed, including cardiac death, which included deaths of unknown cause. ASA was employed in 161 patients and myectomy in 102. Baseline characteristics were similar, but myectomy patients were more likely to have CAD and ASA patients had thicker LV walls. The 30-day post-procedure severe complications (death, stroke, cardiac arrest) were not significantly different between procedures, but the total complication rate was higher after myectomy (28% vs 14%, P = 0.004), which remained true when only the patients done after 2000 are considered. Long-term (median 9 years) follow-up in 99% of the patients showed that yearly all-cause mortality was similar (1.5 ASA, 2.2 myectomy, P = NS), as was cardiac mortality (0.7 ASA vs 1.4 myectomy, P = NS). In the 13 patients with implantable cardioverter defibrillators (ICDs), no appropriate shocks were observed. Also, symptoms, rehospitalization for heart failure, stroke, and myocardial infarction were not different. In the 92% with a late echocardiograms (mean 4 years), provoked LVOT gradients were higher in the ASA patients (19 vs 10 mmHg, P < 0.001). The authors concluded that survival and clinical outcomes were similar in ASA and myectomy patients.
As this study shows, less invasive procedures have great appeal for patients. Once ASA was introduced, it quickly became the predominant procedure when patients were offered a choice. What this experience shows is that this choice was reasonable given the excellent short- and long-term results with ASA. It is not surprising that a percutaneous procedure would have less periprocedural complications, but there has been fear that the induction of a septal MI would lead to long-term ventricular arrhythmias and an increase in late sudden death. This was not observed in this study, and in the patients with ICDs, there was no difference in appropriate shocks during follow up. Another critique of ASA was that the need for a pacemaker afterward would be higher. This also was not observed; 11% of ASA patients and 9% of myectomy patients needed a pacemaker (P = NS).
The strengths of this study are the long follow up and the completeness of the follow-up data. Weaknesses include the retrospective, observational design and that myectomies were done over a longer time period. However, the groups were well-matched, and when the study was censured at year 2000 forward (start of ASA), the results were the same.
The current American College of Cardiology/American Heart Association guidelines recommend myectomy as the procedure of choice and ASA as an alternative for those who cannot, or will not, have myectomy. These data would support both as reasonable first-line therapy. One caveat is that ASA cannot be done in all patients due to variations in septal perforator coronary anatomy. Some patients don’t have one large septal perforator supplying the largest superior portion of the septum. Presumably, myectomy can be done in almost everyone. Some patients are not candidates for either procedure due to more diffuse septal hypertrophy, resulting in more of a cavity obliteration physiology with more diastolic heart failure.
Another issue is what to do with the patients with concomitant CAD. In this study, most of these patients had myectomy with bypass surgery. However, a percutaneous coronary procedure could be feasible in many patients, but there is little experience with this approach currently. In the final analysis, the choice of procedure is complicated, and medical issues as well as patient preference should be considered in the decision. This study provides reassurance that either decision is likely to lead to a good outcome. Finally, the editorial accompanying this paper by two Mayo Clinic cardiologists suggests that the infrequent HPCM patient who would benefit from septal reduction therapy should probably be sent to a center experienced with these procedures.