Abstract Body (Do not enter title and authors here): Background: Previous research has established that a cut-off value of the index of angiographic-derived microcirculatory resistance (AMR) greater than 250 mmHg*s/m is indicative of poorer clinical outcomes in cases of primary PCI. This study aims to investigate the correlation of AMR post elective PCI > 250 mmHg*m/s in coronary flow velocity ratio (CFVR) and high-sensitivity troponin (hsT) peak.

Methods: Between June 2021 and December 2023, a total of 330 patients with successful elective PCI and without side branch occlusion were selected for microcirculation analysis using AngioPlus Core (Shanghai Pulse Medical Technology Inc) in a tertiary cardiology hospital at São Paulo, Brazil. HsT peak, AMR and CFVR were compared.

Results: Our patient cohort was stratified based on post PCI AMR, utilizing a threshold of 250 mmHg*s/m (Figure 1A), with 162 patients in group > 250 mmHg*s/m (mean 299.4 ± 42.5 mmHg*s/m) and 168 patients <250 mmHg*s/m (mean 214.6 ± 28.1 mmHg*s/m). The AMR > 250 mmHg*s/m group exhibited lower CFVR pre PCI (p <0.001, Figure 1B) and post PCI (p <0.001, Figure 1C), associated with a higher peak hsT (p <0.001, Figure 1D).
In relation to AMR and μFR parameters, we found higher μFR (p = 0.005, Figure 2A) in patients with CMD (AMR > 250 mmHg*s/m, figure 2A), but no statistically difference in delta μFR (p = 0.08, Figure 2B). Lower AMR pre PCI (p < 0.001, Figure 2C) and higher delta AMR (p = 0.003, Figure 2D) are associated with AMR > 250 mmHg*s/m.

Conclusion: We demonstrate that an AMR exceeding 250 mmHg*m/s following elective successful PCI is associated with reduced coronary flow velocities and myocardial injury. These indexes have potential utility in clinical practice as risk stratification tools.