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The following is a summary of the ‘Angiography-versus wire-based microvascular resistance index to detect coronary microvascular obstruction associated with ST-segment elevation myocardial infarction,” published in the June 2024 issue of Cardiology by Wang et al.

After ST-segment elevation myocardial infarction (STEMI), microvascular obstruction (MVO) detected by cardiac magnetic resonance (CMR) carries significant prognostic value. While invasive measures like the index of microvascular resistance (IMR) predict MVO, the role of angiography-based microvascular resistance (Angio-IMR) is unclear.

Researchers conducted a prospective study comparing the effectiveness of wire-based and Angio-IMR microcirculatory resistance in detecting MVO.

They scanned patients with a first STEMI and multivessel disease using CMR to spot MVO. During primary percutaneous coronary intervention (PPCI) and 30-day follow-up, IMR and angio-IMR were measured in both the block artery causing STEMI and other non-culprit vessels. 

The results showed that in 58 patients (average age was 60.7 ± 9.9 years, 82% male), angio-IMR and IMR during PPCI correlated well (r=0.70, P<0.001) and showed good agreement (coefficient of agreement 0.58). Both predicted MVO effectively [Angio IMR: AUC 0.79 (95% CI: 0.667–0.928); IMR: AUC 0.70 (95% CI: 0.539–0.853); P= 0.15], with cut-offs at Angio-IMR 40 U and IMR 34 U identifying as best. In non-culprit vessels, both measures also correlated (rho = 0.59, P< 0.001), with lower average values compared to culprit vessels (Angio-IMR: 36 vs. 23; IMR: 39 vs. 22, P<0.001 for both).

Investigators concluded that angio-IMR was a reliable substitute for wire-based IMR forecasting MVO in STEMI cases. A strong correlation between angio-IMR and IMR was shown during acute and subacute phases, regardless of the vessel involved.

Source: internationaljournalofcardiology.com/article/S0167-5273(24)00878-7/abstract#%20