Endothelin-1 and Cardiac Allograft Vasculopathy (CAV)

Phase 4

Completed

Conditions: Cardiac Allograft Vasculopathy

Interventions: Drug: Macitentan

Registration Number: NCT05373108

Lead Sponsor: University of California, Los Angeles

Brief Summary: Many patients with end-stage heart failure, a condition in which the heart fails to pump enough blood to support the body's other organs, are fortunate enough to receive a heart transplant. However, despite taking medicines aimed at blunting the immune system's response to the donor heart, some of them will develop transplant-related disease in the coronary arteries supplying their hearts. Fifty years after the first human-to-human heart transplant, this disorder-cardiac allograft vasculopathy (CAV)-remains a leading cause of long-term death and has been coined the 'Achilles' Heel' of heart transplantation. Indeed, a better understanding of how CAV occurs and improved therapies to prevent and/or slow its development are desperately needed to meaningfully impact patient outcomes.

Endothelin-1 (ET-1) is a key molecular regulator of arterial health, and our prior data suggests that it is associated with accelerated CAV. In this particular study of recent heart transplant recipients, we are asking: Does ET-1 contribute to the coronary artery's capacity to dilate/constrict? To answer this question, during the cardiac catheterization at 1 year post-transplant (standard of care), we will measure blood levels of ET-1 and perform an invasive evaluation of coronary vasomotor function inn a consecutive subset of patients who will have received a 1-week course of the oral endothelin receptor antagonist (macitentan) prior this catheterization, which will allow us to test how much ET-1 contributes to coronary responsiveness.

The findings from this study may provide the necessary foundation to study whether endothelin receptor antagonists are able to effectively reduce the rate of accelerated CAV.

Detailed Description: Not available

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 19

Inclusion Criteria

1. New heart transplant recipients already enrolled into a prospective cohort (parent) study
1a) Underwent baseline coronary angiography within the first 4 months of heart transplantation
1b) Have yet to complete 1-year coronary angiogram
1. ≥18 years old
1. Have a serum creatinine < 2.0 mg/dL (to minimize risk of contrast-induced nephropathy)
1. Able to provide informed written consent.

Exclusion Criteria

1. Multi-organ transplant
1. Transplant-related complications and comorbidities that preclude the ability to safely perform an invasive coronary evaluation in the cardiac catheterization laboratory
1. Pregnant women due to possible fetal harm; all women of childbearing potential must have a negative pregnancy test within 1 week of starting Macitentan, and 30 days after completing the one-week course of Macitentan.
1. Patients who are taking potent CYP3A4 inhibitors (e.g. ketoconazole, ritonavir) as these drugs can expose one to higher levels of macitentan
1. Cirrhosis or baseline liver function tests (AST/ALT) > 3x the upper limit of normal

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Intervention Arm	Macitentan	A consecutive subset of eligible patients based on inclusion/exclusion criteria will receive a 1-week course of Macitentan (10 mg po daily) prior to their routine 1-year coronary angiogram (7th and final dose of Macitentan will occur on the day of the angiogram).

Primary Outcome Measures

Name	Time	Method
Macitentan: Nitroglycerin (NTG) Luminal Dilation Ratio as Proportion of Vasomotor Tone Attributable to Endothelin-1 (ET-1)	End of study week 1 (time of 1 year post-transplant coronary angiogram)	Macitentan: NTG luminal volume dilation ratio on Intravascular Ultrasound (IVUS). Vasodilation achieved by Macitentan was compared with that after intracoronary nitroglycerin, a maximal dilator of epicardial arteries, to determine the relative contribution of ET-1 to the overall resting vasomotor tone. The contribution of ET-1 to resting vasomotor tone is expressed as the ratio of dilation to Macitentan over the dilation to nitroglycerin.

Secondary Outcome Measures