Left ventricular outflow tract (LVOT) obstruction is an integral component of hypertrophic cardiomyopathy (HCM). Both chemical myomectomy and alcohol septal ablation (ASA) have been shown effective in the reduction of residual gradients and symptoms in several studies and clinical registries, and are normally reserved for patients who continue experiencing symptoms despite medical treatment. 

Even though hemodynamic predictors of cardiovascular events (such as post ASA residual gradient) have been looked into, little is known about the impact of other objective parameters that could be measured by heart catheterization. The aim of this study was to assess whether changes before and after ASA might influence outcomes at long term. 

Data from symptomatic HCM patients who had received ASA and heart catheterization by transseptal route (more accurate than the retro-aortic approach) at the Mayo Clinic were gathered retrospectively. Aortic pressure was measured (systolic and diastolic), as well as LV pressure (systolic, diastolic and end-diastolic), atrial (A, V and mean waves) and LVOT gradient (peak to peak). 

Mean patient age was 67.3±4.7, with mean body mass index (BMI) 30.2, and 46.2% were women. 65.2% were hypertensive and 42% had known heart disease. Resting gradients were >50 mmHg in 56.4% of cases, with mean septal thickness 9.2 mm.  ASA patients saw a reduction in all variables except for LV end diastolic pressure. P-P gradient saw the biggest change (76.4%), followed by atrial V wave (19.1%) and pulse pressure (-17%).

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At 10 year followup, survival was over 50%. Baseline mean LVOT pressure gradient >19 mmHg was associated with adverse events and survival predictors were identified as percentage change in pulse pressure (P=0.31) and LVOT gradient (P<0.001). 

Multivariable analysis showed predictors of mortality at long term were baseline left atrial V wave pressure > median (28 mm Hg; HR, 2.36 [95% CI, 1.17–4.76]; P=0.016), baseline mean LA pressure > median (19 mm Hg; HR, 2.70 [95% CI, 1.33–5.50]; P=0.006), pulse pressure increase ≤19.3% (HR, 2.09 [95% CI, 1.05–4.16]; P=0.035), and LVOT gradient reduction ≤82% (HR, 2.74 [95% CI, 1.37–5.50]; P=0.005).

NYHA functional class was 2.97±0.31 at baseline, 1.47±0.67 at 30 days, and 1.77±0.7 at last followup.

Conclusion

This retrospective study showed that a group of patients with specific hemodynamic variables saw improved symptoms assessed by functional class, as well as improved survival at long term. This was especially true for patients with low atrial V wave, low LA baseline pressure, significant LVOT reduction and increased pulse pressure. 

Dr. Omar Tupayachi.
Member of the Editorial Board of SOLACI.org.

Original Title: Hemodynamic Predictors of Outcome Following Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy.

Reference: Alabdaljabar, Mohamad S et al. “Hemodynamic Predictors of Outcome Following Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy.” Circulation. Cardiovascular interventions vol. 16,8 (2023): e013068. doi:10.1161/CIRCINTERVENTIONS.123.013068.

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