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Published on: June 28, 2019
Prognostic Implications of Microvascular Resistance Reserve in Symptomatic Patients With
Seung Hun Lee1, Ki Hong Choi2, David Hong2
1Division of Cardiology, Department of Internal Medicine, Heart Center, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, South Korea.
Insights
Microvascular resistance reserve (MRR) predicts adverse cardiovascular events in stable ischemic heart disease (IHD) patients. This coronary microvascular function index is valuable regardless of epicardial stenosis severity.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Diagnostic Tools
Background:
- Microvascular resistance reserve (MRR) assesses coronary microcirculatory function independently of epicardial stenosis.
- Limited data exists on MRR's prognostic value in stable ischemic heart disease (IHD).
Purpose of the Study:
- To evaluate clinical outcomes based on MRR in stable IHD patients.
- To assess MRR's role with or without significant epicardial coronary artery stenosis.
Main Methods:
- 547 patients with suspected stable IHD underwent echocardiography and invasive physiological assessment.
- Significant epicardial stenosis defined as FFR ≤0.80; coronary microvascular dysfunction (CMD) as MRR ≤3.0.
- Primary outcome: major adverse cardiovascular events (MACE) including cardiovascular death, MI, repeat revascularization, and heart failure admission.
Main Results:
- 200 patients (36.6%) had CMD (MRR ≤3.0).
- MRR correlated with microcirculatory resistance, natriuretic peptide levels, and diastolic dysfunction, but not FFR.
- Decreased MRR was independently associated with increased MACE risk (HR: 1.23 per 1-U decrease).
- CMD increased MACE risk in both FFR >0.80 and FFR ≤0.80 groups.
Conclusions:
- Reduced MRR is linked to diastolic dysfunction and elevated filling pressures.
- Coronary microvascular dysfunction (CMD) identified by MRR independently predicts MACE in stable IHD patients.
- MRR's prognostic value is significant irrespective of epicardial coronary artery stenosis.
Background:
Microvascular resistance reserve (MRR) is a novel index reflecting coronary microcirculatory function, irrespective of epicardial coronary artery stenosis. There is limited evidence regarding whether MRR can be an independent prognostic tool in patients with stable ischemic heart disease (IHD).
Objectives:
The aim of this study was to evaluate clinical outcomes according to MRR in patients with stable IHD accompanied with or without significant epicardial coronary artery stenosis.
Methods:
The present study included 547 consecutive patients undergoing systematic echocardiographic and invasive physiological assessment for suspected stable IHD. Significant epicardial coronary artery stenosis was defined as fractional flow reserve (FFR) ≤0.80. Coronary microvascular dysfunction (CMD) was defined as MRR ≤3.0. The primary outcome was major adverse cardiovascular events (MACE), a composite of cardiovascular death, myocardial infarction, repeat revascularization, and admission for heart failure.
Results:
Among the study group, 172 patients (31.4%) had FFR ≤0.80, and 200 patients (36.6%) had CMD defined by MRR ≤3.0. MRR showed no significant correlation with FFR (R = -0.031; P = 0.469), but it was significantly correlated with the index of microcirculatory resistance (R = -0.353; P < 0.001), N-terminal pro-B-type natriuretic peptide (R = -0.296; P < 0.001), left ventricular filling pressure (E/e' ratio) (R = -0.224; P < 0.001), and diastolic dysfunction grade (P < 0.001). During a median follow-up period of 3.3 years (Q1-Q3: 2.0-4.5 years), MRR was significantly associated with MACE risk (HR: 1.23 per 1-U decrease; 95% CI: 1.12-1.36; P < 0.001). CMD defined by MRR ≤3.0 was associated with an increased MACE risk for both FFR >0.80 (41.0% vs 26.0%; adjusted HR: 1.59; 95% CI: 1.07-2.35; P = 0.021) and FFR ≤0.80 (34.7% vs 14.8%; adjusted HR: 2.32; 95% CI: 1.12-4.82; P = 0.024).
Conclusions:
Decreased MRR was associated with the presence of cardiac diastolic dysfunction as well as increased left ventricular filling pressure. The presence of CMD defined by MRR was independently associated with the risk for a composite of cardiovascular death, myocardial infarction, repeat revascularization, and admission for heart failure in patients with stable IHD, irrespective of significant epicardial coronary artery stenosis. (Prognostic Impact of Cardiac Diastolic Function and Coronary Microvascular Function [DIAST-CMD]; NCT05058833).
