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Coronary Venous Pressure and Microvascular Hemodynamics in Patients With Microvascular Angina: A Randomized Clinical
Helen Ullrich1, Philipp Hammer2,3, Maximilian Olschewski1
1Department of Cardiology, Cardiology I, University Medical Center Mainz, Mainz, Germany.
Insights
Increasing coronary venous pressure reduced microvascular resistance in patients with microvascular angina. This finding suggests a potential new therapeutic mechanism for this challenging cardiovascular condition.
Area of Science:
- Cardiovascular Physiology
- Coronary Circulation
- Microvascular Function
Background:
- The role of coronary venous circulation in myocardial perfusion is not well understood.
- Microvascular angina remains a therapeutic challenge due to poorly understood pathophysiology.
Purpose of the Study:
- To investigate if elevated coronary venous pressure can modify microvascular resistance in patients diagnosed with microvascular angina.
- To explore the potential therapeutic implications of modulating coronary venous pressure.
Main Methods:
- A blinded, sham-controlled, crossover, randomized clinical trial was conducted with 20 patients.
- Coronary sinus (CS) pressure was increased using an occluding balloon, with measurements taken at rest and during hyperemia.
- Key hemodynamic parameters including coronary pressures and mean transit time were assessed.
Main Results:
- CS balloon inflation significantly increased CS pressure and decreased hyperemic distal coronary pressure and mean transit time.
- Coronary sinus occlusion resulted in a significant reduction in both resting and hyperemic coronary resistance.
- The primary endpoint, hyperemic coronary resistance, decreased significantly (P < .001) with CS occlusion.
Conclusions:
- Elevated coronary venous pressure effectively reduces microvascular resistance in patients with microvascular angina.
- This mechanism presents a novel therapeutic avenue for managing microvascular angina.
- Further research is warranted to translate these findings into clinical practice.
Importance:
The role of the coronary venous circulation in regulating myocardial perfusion and its potential in treating microvascular angina is unexplored.
Objective:
To evaluate whether an increase in coronary venous pressure modifies microvascular resistance in patients with microvascular angina.
Design, Setting, And Participants:
This was a blinded, sham-controlled, crossover, randomized clinical trial that enrolled participants between November 2021 and January 2023. Participants for this physiology end point study were recruited from the Cardiology Center of the University of Medicine in Mainz, Germany. Patients with moderate/severe angina pectoris (Canadian Cardiovascular Society class 2-4) due to microvascular dysfunction (as defined by the thermodilution-based index of microvascular resistance >25 mm Hg × s). Exclusion criteria were epicardial coronary disease, second- and third-degree atrioventricular block, severe valvular heart disease, cardiomyopathy, and pulmonary or kidney disease.
Intervention:
Inflation of an undersized balloon placed in the cardiac coronary sinus (CS), hereafter referred to as balloon and the deflated balloon in the right atrium, referred to as sham. Measurements were performed at rest and during maximal coronary hyperemia. Both patients and final assessors were blinded to the randomization sequence.
Main Outcomes And Measures:
Hemodynamic parameters, including aortic (Pa) and distal (Pd) coronary pressure, coronary sinus pressure (Pcs), right atrial pressure (Pra), and the mean transit time (inverse of blood flow [Tmn]), were measured.
Results:
A total of 20 patients (median [IQR] age, 69 [64-75] years; 11 female [55.0%]) were included in the study. Two patients (10%) had diabetes, 6 (30%) had hypercholesterolemia, 15 (75%) had hypertension, and 3 (15%) were active smokers. The inflation of the CS balloon caused a significant increase in CS pressure at rest and during hyperemia (300% and 317% increase, respectively, compared with sham, both P < .001), a decrease in hyperemic distal coronary pressure (median [IQR], sham: 92 [80-100] mm Hg; balloon: 79 [75-93] mm Hg; P = .01) and mean transit time (sham: 0.39 [0.23-0.62] s; balloon: 0.26 [0.17-0.46] s; P = .008). As a result, CS occlusion led to a decrease in both resting coronary resistance (median [IQR], sham: 59 [37-87] mm Hg × s; balloon: 42 [31-67] mm Hg × s; P = .005) and the primary end point hyperemic coronary resistance (mean [IQR], sham: 31 [23-53] mm Hg × s; balloon: 14 [8-26] mm Hg × s; P < .001).
Conclusion And Relevance:
Increased coronary venous pressure led to a reduction of microvascular resistances in patients with microvascular angina, a mechanism with potential implications for the therapy of this complex disease.
Trial Registration:
ClinicalTrials.gov Identifier: NCT05034224.
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