A novel risk model to predict all-cause mortality in patients undergoing percutaneous transluminal septal myocardial ablation for hypertrophic obstructive cardiomyopathy

Background and purpose: Hypertrophic obstructive cardiomyopathy (HOCM) is a global genetic myocardial disease. In clinical practice, an indicator that could be used to identify suitable patients for percutaneous transluminal septal myocardial ablation (PTSMA) and assess their long-term prognosis is important for cardiologists. HOCM patients undergoing PTSMA, poor long-term prognosis has been associated with higher left ventricular outflow tract gradient (LVOTG) and interventricular septal thickness (IVST). In this retrospective, multicenter study, we aimed to investigate the association between TG (TG = IVS thickness × LVOT gradient) index and acute- or long-term outcomes of HOCM patients after PTSMA and further investigate the interaction effects of LVOTG and IVST. Methods: The study design is based on four tertiary centers from Mid-China, and a total of 284 HOCM patients (132 males, average age 54.80 ± 11.98 years) were treated with PTSMA. A new clinic index (TG = IVS thickness × LVOT gradient) was designed. Both 30-day major cardiovascular adverse events and all-cause mortality of the HOCM patients were analyzed. Cox proportional hazards regression model adjusting for potential risk factors was applied to explore the hazard ratio (HR) for all-cause mortality. Results: Total alcohol injection volume was 2.201 ± 1.025 mL. LVOTG and IVST were reduced to 40.11 ± 24.44 mmHg and 17.68 ± 4.07 mm at the last clinical check-up, respectively. Patients with low IVST (≤20 mm) or low TG index (≤1,683) had a higher rate of PTSMA-contributable complications and a higher need for a permanent pacemaker. Within the 903 patient-years follow-up, a total of 21 (9.8%) deaths occurred. The number of deaths per 100 patient-years was 0.65 and 4.06 in the high versus low TG index groups. The 8-year OS rate was 48.95% (95% CI = 39.07%–57.75%) versus 82.63% (95% CI = 74.99%–86.66%) in the high versus low TG groups, respectively (log-rank P < 0.001). The patients with both high LVOTG (>82 mmHg) and high IVST had the highest risk of all-cause mortality (HR: 18.63 vs low LVOTG, 95% CI = 1.09–319.15). Conclusions: The 8-year OS rate was markedly higher in patients with a low TG index (≤1,683) (48.95%) versus in patients with a high TG index (>1,683 group) (82.63%). The TG index could be a useful tool in the evaluation of HOCM patients for suitability for PTSMA.