Midterm results of different treatment methods for myocardial bridging
in patients after septal myectomy
Background: Myocardial bridging (MB) is commonly treated in patients
with hypertrophic cardiomyopathy (HCM). However, whether and how MB
should be treated in patients with hypertrophic obstructive
cardiomyopathy (HOCM) who underwent septal myectomy remain unclear.
Methods: A total of 823 adults with HOCM who underwent septal myectomy
at the Fuwai Hospital from 2011 to 2017 were retrospectively studied.
Results: Overall, 31 events occurred: 24 patients died and 7 had
nonfatal myocardial infarction (MI). The 3-year cumulative event-free
survival of all-cause death (97.9% vs 100% vs 100% vs 98.4%, p=0.89)
and cardiovascular death (98.3% vs 100% vs 100% vs 98.4%, p=0.63)
were similar among the four groups (non-MB, CABG, unroofing, untreated,
respectively). The 3-year cumulative event-free survival of nonfatal MI
(100% vs 97.5% vs 98.0% vs 89.9%, p<0.001) and combined
endpoints (97.9% vs 97.5% vs 98.0% vs 88.4%, p=0.02) were
significantly lowest in untreated MB. Cox regression analysis indicated
that untreated MB was a significant independent predictor of combined
endpoints (hazard ratio [HR]: 4.06, 95% confidence interval
[CI]: 1.60–10.32, p<0.001). Moreover, 49 patients
underwent coronary artery computed tomography after surgery. The patency
rate of the saphenous vein graft (SVG) was significantly higher than
that of the left internal mammary artery (LIMA) (13.3% vs 84.2%,
p<0.001). No MB was detected in the unroofing group.
Conclusions: Surgical MB treatment could be beneficial and performed
safely during septal myectomy. Myocardial unroofing is the recommended
treatment for MB, and unroofing when technically possible may be
preferable for long-term outcomes.