Summary
A single-centre retrospective preprint found that modified Morrow myectomy produced lower one-year LVOT gradients, while Liwen ablation was associated with fewer new conduction abnormalities and shorter procedures and hospital stays. The authors describe the findings as a trade-off requiring prospective confirmation.
A single-centre retrospective study has compared percutaneous Liwen ablation with modified Morrow myectomy for obstructive hypertrophic cardiomyopathy, finding a clear difference between the procedures after one year. Myectomy produced more complete relief of left ventricular outflow tract obstruction, while Liwen ablation was associated with fewer new conduction abnormalities, shorter procedures and shorter hospital stays.
The findings, posted as a medRxiv preprint, came from 211 patients treated between 2018 and 2023: 124 received Liwen ablation and 87 underwent modified Morrow myectomy. The one-year longitudinal analysis included 133 patients with serial follow-up data.
Different outcomes at one year
Hypertrophic cardiomyopathy causes abnormal thickening of the heart muscle. In its obstructive form, thickened muscle near the left ventricular outflow tract (LVOT)—the route blood takes from the heart into the aorta—can restrict blood flow. The LVOT gradient measures the pressure difference created by that obstruction; a lower value generally indicates less obstruction.
Both procedures reduced the LVOT gradient, but the study found that their trajectories differed over follow-up. At one year, the covariate-adjusted mean gradient was 1.3 mmHg after modified Morrow myectomy, compared with 16.1 mmHg after Liwen ablation, a difference reported as statistically significant (P<0.001).
The study also reported the proportion of patients who reached an LVOT gradient below 30 mmHg: 96% after myectomy and 82% after Liwen ablation. The reported nominal P value for this comparison was 0.308.
The pattern was reversed for new conduction abnormalities, which affect the electrical signalling system that coordinates the heartbeat. The adjusted one-year predicted probability was 5% in the Liwen group and 62% in the myectomy group (P<0.001). No permanent pacemaker implantations occurred in the Liwen group.
Liwen ablation also had a shorter reported procedure duration—80 minutes compared with 185 minutes for myectomy—and a shorter hospital stay, 11 days compared with 16 days. Serious adverse-event rates were similar at 8.1% and 9.2%, although the source says that the types of events differed between the groups.
How the procedures differ
Modified Morrow myectomy is an operation that removes part of the thickened septal muscle contributing to the obstruction. Liwen treatment is a percutaneous intramyocardial septal radiofrequency ablation procedure, using radiofrequency energy to treat septal tissue without the same form of surgical muscle removal.
The results therefore point to a clinical trade-off in this cohort. Myectomy achieved the lower residual pressure gradient, while Liwen ablation was associated with fewer conduction abnormalities and a shorter treatment and recovery pathway. These outcomes concern different aspects of treatment: hemodynamic relief on one side and electrical-conduction safety and procedural burden on the other.
What the study design means
This was a retrospective observational cohort from one hospital, not a prospective interventional clinical trial. The researchers used linear mixed-effects models and generalized estimating equations to analyse repeated outcomes and adjusted the comparison for baseline covariates.
The one-year analysis included 75 Liwen patients and 58 myectomy patients, fewer than the 211 patients in the overall cohort. That difference is important when interpreting the longitudinal results. Treatment selection was also examined through existing clinical records rather than assigned prospectively in a trial, so the comparison describes outcomes in this cohort rather than establishing that one procedure causes the observed differences.
The authors conclude that modified Morrow myectomy delivered more complete LVOT gradient reduction at one year, whereas Liwen ablation had fewer conduction abnormalities, shorter procedures and shorter hospital stays. They say prospective studies are needed to confirm the findings and support treatment selection.