Prognostic value of the index of microcirculatory resistance after percutaneous coronary intervention in patients with non-ST-segment elevation acute coronary syndrome

BACKGROUND

The prognostic value of physiological indices in non-ST-segment elevation acute coronary syndrome (NSTE-ACS) patients undergoing percutaneous coronary intervention (PCI) is unknown. We investigated the prognostic efficacy of physiological indices obtained after PCI in patients with NSTE-ACS.

METHODS

Eighty-three patients (men: n = 70, age: 63.7 ± 9.7 years) undergoing PCI for NSTE-ACS within 48 hr postadmission were investigated. Fractional flow reserve (FFR), coronary flow reserve (CFR), and the index of microcirculatory resistance (IMR) of the culprit vessels were measured after the completion of PCI. The patients were clinically followed up to determine major cardiac adverse events (MACE), including death, congestive heart failure requiring hospitalization, and remote coronary revascularization.

RESULTS

The median FFR, CFR, and IMR values were 0.90 (interquartile range [IQR] 0.86-0.95), 2.38 (IQR 1.75-4.17), and 22.9 (IQR 11.2-31.5), respectively. During a median follow-up of 20.7 months, 19 MACEs (22.9%) were documented. No significant difference in baseline patient characteristics, except for age, was detected between patients with and without MACE. Patients with MACE showed higher IMR and lower CFR than those without (IMR: 27.2 vs. 16.3; P = 0.001, CFR: 1.82 vs. 2.55; P = 0.04), whereas FFR was not significantly different (0.92 vs. 0.89; P = 0.72), irrespective of the MACE occurrence. Post-PCI IMR was the only independent predictor of MACE (hazard ratio 1.033, 95% confidence interval 1.013-1.052, P = 0.001). The MACE-free survival was significantly worse in patients with high post-PCI IMR (χ² 7.12; P = 0.008).

CONCLUSION

Post-PCI IMR may help identify patients at high risk for subsequent adverse coronary events who require adjunctive therapeutic strategies.

Large coronary thrombus: A safe and effective approach using percutaneous coronary intervention after vigorous antithrombotic therapy

After percutaneous coronary intervention, high thrombotic burden is the strongest correlate for extensive microvascular obstruction, distal embolization, and the no-reflow phenomenon. It is suggested that in these cases conventional thrombectomy methods may mechanically dislodge thrombi downstream and decrease myocardial perfusion. The following report includes an alternative approach in which a coronary vessel with large thrombotic burden was treated successfully first with vigorous pharmacological antithrombotic and antiplatelet therapy followed by coronary intervention after several days.