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A pilot study on coronary microvascular dysfunction in obstructive hypertrophic cardiomyopathy: impact of
Taikan Terauchi1, Daigo Hiraya2, Kyohei Usami1
1Department of Cardiology, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 3058575, Japan.
Insights
Percutaneous transluminal septal myocardial ablation (PTSMA) improved coronary microvascular dysfunction (CMD) in obstructive hypertrophic cardiomyopathy (oHCM) patients. This septal reduction therapy reduced pressure gradients and enhanced microcirculation.
Area of Science:
- Cardiology
- Cardiovascular Research
- Interventional Cardiology
Background:
- Coronary microvascular dysfunction (CMD) is recognized in coronary artery disease but poorly understood in obstructive hypertrophic cardiomyopathy (oHCM).
- The effect of percutaneous transluminal septal myocardial ablation (PTSMA) on CMD in oHCM remains unevaluated.
Purpose of the Study:
- To investigate the impact of PTSMA on CMD in patients with oHCM.
- To assess changes in microcirculatory function following PTSMA.
Main Methods:
- PTSMA was performed on 10 oHCM patients between October 2023 and May 2024.
- Invasive assessment of CMD using a pressure guidewire in the left anterior descending artery (LAD) before and after PTSMA.
- Measurements included resting full-cycle ratio (RFR), fractional flow reserve (FFR), coronary flow reserve (CFR), and index of microcirculatory resistance (IMR).
Main Results:
- Pre-PTSMA, patients showed reduced CFR (1.8) and elevated IMR (31), indicating CMD, despite normal RFR and FFR.
- Post-PTSMA, the left ventricular pressure gradient significantly decreased (from 44 to 5 mmHg).
- Microcirculatory function improved, with increased CFR (to 2.5) and decreased IMR (to 22).
Conclusions:
- Myocardial hypertrophy in oHCM contributes to both left ventricular outflow tract obstruction and CMD.
- PTSMA effectively reduces the left ventricular pressure gradient in oHCM.
- This study demonstrates that PTSMA improves coronary microvascular dysfunction in patients with oHCM.
Abstract:
Coronary microvascular dysfunction (CMD) is well-characterized in the context of coronary artery disease, but its relationship to obstructive hypertrophic cardiomyopathy (oHCM) is poorly understood. In addition, the impact of percutaneous transluminal septal myocardial ablation (PTSMA) on CMD has not been fully evaluated. Between October 2023 and May 2024, PTSMA was performed on 10 patients with oHCM. A pressure guidewire in the left anterior descending artery (LAD) was used to invasively assess CMD before and after the procedure. Measurements were recorded for resting full-cycle ratio (RFR), fractional flow reserve (FFR), coronary flow reserve (CFR), and index of microcirculatory resistance (IMR). The 10 patients had a median age of 66 [57-75] years, with a resting left ventricular pressure gradient of 44 [17-84] mmHg, measured via catheterization. Prior to PTSMA, the RFR measured in the LAD was 0.93 [0.91-0.96], and the FFR was 0.95 [0.92-0.95], which were both within normal limits. However, the CFR was reduced to 1.8 [1.6-2.1], and the IMR was elevated to 31 [25-39], which indicated CMD. Post-procedure, the left ventricular pressure gradient decreased to 5 [2-8] mmHg, CFR improved to 2.5 [2.2-3.6], and IMR decreased to 22 [17-26], indicating improvement in CMD. In patients with oHCM, myocardial hypertrophy contributes to left ventricular outflow tract obstruction and CMD. This study demonstrated that PTSMA as a septal reduction therapy improved the left ventricular pressure gradient and CMD.
