Post-COVID Microvascular Dysfunction Index (Stress Perfusion Surrogate) Calculator

Quantitative CMR Perfusion Inputs (preferred) Enter global myocardial blood flow (MBF) from quantitative CMR perfusion mapping. Post-COVID Microvascular Dysfunction (Stress Perfusion Surrogate): Explanation and Clinical Context This calculator estimates microvascular function using quantitative stress perfusion metrics. The primary output is myocardial perfusion reserve (MPR), computed from global stress and rest myocardial blood flow (MBF) by cardiovascular magnetic resonance (CMR).

Lower MPR values are associated with impaired coronary microvascular function. Post-COVID cohorts have repeatedly demonstrated reduced stress perfusion and, in some studies, lower MPR versus non-COVID controls. How to interpret the results • MPR: Values <2.0 are commonly considered abnormal and associated with adverse prognosis in non-obstructive cohorts; values 2.0–2.5 are borderline; values ≥2.5 are typically regarded as preserved microvascular function in contemporary quantitative CMR practice. • Stress MBF: Values <~1.7 mL/g/min suggest impaired hyperemic flow or submaximal vasodilation; normal physiology is usually higher under adequate pharmacologic stress. • Global CFR (optional): If derived from coronary sinus flow (CSF), a g-CFR <~1.7–2.0 is often considered impaired or borderline, respectively, and has been linked to worse outcomes in mixed cardiac cohorts. • Surrogate Index (0–100): A continuous, non-validated scale derived from MPR to aid communication/triage: higher numbers indicate greater likelihood/severity of microvascular impairment.

Use alongside clinical judgment and imaging reports, not as a stand-alone diagnostic or prognostic tool. Clinical caveats Quantitative perfusion depends on adequate stress (agent/dose), heart rate–blood pressure product, hematocrit, and acquisition/analysis pipelines. Always interpret in the context of symptoms, ECG, troponin, edema/T1/T2, scar (LGE), wall motion, and epicardial disease exclusion.

Post-COVID patients may exhibit CMD despite normal volumetric function and absence of edema/scar, so a perfusion-first approach can be helpful, but confirmation and management should follow current INOCA/CMD guidance. References 1) Knott KD, et al. Circulation 2020 – Abnormal MPR (<2) associated with worse outcomes even without perfusion defects.

2) Kotecha T, et al. JACC Cardiovasc Imaging 2019 – Optimal MPR cutoff ≈1.96 vs invasive physiology. 3) SCMR/consensus & contemporary reviews on quantitative perfusion thresholds and reporting.

4) Kanaji Y, et al. 2022 – Prognostic value of CSF-derived hyperemic flow and g-CFR; impaired <~1.6–1.7 associated with events. 5) Catania R, et al.

RSNA 2025 – Technical review noting stress MBF expectations and MPR ≈2.0 cutoffs. 6) Johansson RS, et al. 2025; Drakos S, et al.

2021; Karagodin I, et al. 2024 – Post-COVID studies reporting reduced stress perfusion/MPR by quantitative CMR.