Background: Despite growing evidence of its clinical implications, assessment of coronary microvascular dysfunction (CMD) remains limited in routine clinical practice. Hence, there is an increasing interest in angiography-derived indices to encourage assessment of CMD in the cardiac catheterisation laboratory.
Aims: We investigate here an alternative approach, using a combination of pressure-wire-based assessment of distal coronary pressure (P) and an angiography-derived surrogate of coronary flow, to derive a hybrid index of microcirculatory resistance (IMR).
Methods: Patients enroled prospectively under the Oxford Acute Myocardial Infarction (OxAMI) study were included in the OxAMI HYBRID substudy. The accuracy of IMR was assessed in diagnosing CMD using bolus thermodilution-based Index of Microcirculatory Resistance (IMR) as a reference. The accuracy of IMR was then compared against a fully angiography-derived index of microvascular resistance (IMR).
Results: One hundred and eighty six patients were enroled, of which 121 with acute coronary syndrome and 65 with stable coronary artery disease. A total of 240 vessel analyses were performed. Both IMR and IMR correlated with IMR (rho = 0.71, p < 0.001 and rho = 0.71, p < 0.001 respectively) and showed good and comparable overall diagnostic accuracy in predicting IMR ≥ 25 (80.8% and 83.1% respectively) with a receiver operator curve (ROC) analyses showing similar AUC of 0.86 (95% CI 0.82-0.91, p < 0.001) for IMR and 0.86 (95% CI 0.809-0.906, p < 0.001) for IMR, p for comparison = 0.641.
Conclusion: Both approaches, IMR and IMR are viable and comparable indices correlating with bolus thermodilution-based IMR and retaining good diagnostic accuracy. IMR specifically is a simple alternative to conventional bolus thermodilution-based IMR applicable to any pressure wire system.
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http://dx.doi.org/10.1002/ccd.31311 | DOI Listing |
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