Early quantitative stress-perfusion cardiac magnetic resonance reveals perfusion abnormalities consistent with coronary microvascular dysfunction in MINOCA patients with otherwise normal cardiac magnetic resonance findings.
Early quantitative stress-perfusion CMR identifies reduced stress MBF and MPR in MINOCA patients with otherwise normal conventional CMR findings, revealing perfusion abnormalities consistent with CMD in nearly half of these patients.
Key Findings
Results
MINOCA patients with normal conventional CMR findings had significantly lower myocardial perfusion reserve (MPR) compared to healthy controls.
MPR was 1.88 ± 0.59 in MINOCA patients versus 2.30 ± 0.55 in controls (p = 0.013)
23 MINOCA patients were compared with age- and sex-matched healthy controls without coronary artery disease confirmed by coronary CT angiography
Controls were confirmed free of coronary artery disease via coronary CT angiography
MPR was derived using fully automated quantitative perfusion analysis from dual-sequence first-pass perfusion CMR
Results
MINOCA patients had significantly lower stress myocardial blood flow (MBF) compared to healthy controls, while rest MBF was similar between groups.
Stress MBF was 2.56 ± 0.81 mL/g/min in MINOCA patients versus 2.96 ± 0.53 mL/g/min in controls (p = 0.044)
Rest MBF was similar between MINOCA patients and controls (no significant difference reported)
Stress perfusion was induced using regadenoson during dual-sequence first-pass perfusion CMR
The pattern of reduced stress MBF with preserved rest MBF is consistent with microvascular rather than resting ischemia
Results
43% of MINOCA patients with normal conventional CMR had quantitative perfusion findings consistent with coronary microvascular dysfunction (CMD), compared with none of the controls.
43% of the 23 MINOCA patients met previously proposed CMR thresholds for CMD
0% of matched healthy controls met CMD thresholds
CMD classification was based on previously proposed CMR thresholds applied to quantitative MBF and MPR values
This finding suggests microvascular dysfunction may contribute to myocardial injury in a substantial subset of MINOCA patients
Methods
Of 46 consecutive MINOCA patients referred for CMR, 23 (50%) had entirely normal findings on conventional CMR at rest and were included in the quantitative perfusion analysis.
46 consecutive MINOCA patients were referred for CMR between 2021 and 2024
Normal conventional CMR was defined as absence of edema, late gadolinium enhancement, or other structural abnormalities
The 23 included patients had a mean age of 63 ± 10 years and 61% were female
CMR was performed a median of 15 days (IQR 10–37) after hospital admission
Methods
Quantitative stress-perfusion CMR using fully automated analysis was feasible in the early post-MINOCA setting, performed a median of 15 days after admission.
Median time from admission to CMR scan was 15 days (IQR 10–37 days)
Fully automated quantitative perfusion analysis was used to quantify MBF and MPR
Dual-sequence first-pass perfusion CMR at rest and during regadenoson stress was employed in all participants
The study demonstrates the applicability of Q-CMR in the subacute phase following MINOCA presentation
What This Means
This research suggests that a specialized heart imaging technique called quantitative stress-perfusion cardiac MRI (Q-CMR) can detect blood flow problems in patients who have had a heart attack despite having open (non-obstructed) coronary arteries — a condition known as MINOCA. In this study, half of MINOCA patients had a completely normal standard cardiac MRI showing no scarring, swelling, or structural damage. Among this group with 'normal' standard MRI results, Q-CMR revealed that blood flow to the heart muscle during stress was significantly lower than in healthy people of similar age and sex, even though blood flow at rest was normal. Nearly half (43%) of these patients met established criteria for coronary microvascular dysfunction (CMD), a condition where the tiny blood vessels of the heart do not work properly, compared to none of the healthy controls.
This matters because MINOCA is a puzzling diagnosis — patients clearly had a heart attack, but standard tests don't show an obvious blockage. This study suggests that for many of these patients, the problem may lie in the microscopic blood vessels rather than the large coronary arteries. Standard cardiac MRI, which looks for scarring and inflammation, misses this entirely. The Q-CMR technique — which measures how much blood flows into the heart muscle during a chemical stress test — may help identify the underlying cause in patients who would otherwise be left without a clear explanation for their heart attack.
The findings are important because identifying CMD as a cause of MINOCA could potentially guide treatment decisions and help doctors better understand and manage this under-recognized condition. The study was relatively small (23 MINOCA patients), so larger studies are needed to confirm these results and determine whether treating CMD in MINOCA patients improves outcomes.
Sahar R, Lenell J, Lindahl B, Montelius A, Berglund J, Grinnemo K, et al.. (2026). Early quantitative stress-perfusion cardiac magnetic resonance reveals perfusion abnormalities consistent with coronary microvascular dysfunction in MINOCA patients with otherwise normal cardiac magnetic resonance findings.. Scientific reports. https://doi.org/10.1038/s41598-026-67231-4