Abstract 14294: Microvascular Resistance Index Immediately after Primary Percutaneous Coronary Intervention Predicts the Presence of Microvascular Obstruction in Patients With ST-elevation Acute Myocardial Infarction Achieving TIMI Grade 3 Reperfusion
Background: It has been reported that the presence of microvascular obstruction (MVO) after acute myocardial infarction (AMI) is associated with larger infarct size, poorer clinical outcomes, and worse left ventricle remodeling. Contrast-enhanced magnetic resonance imaging (Ce-MRI) allows us to detect microvascular damage with the transmural extent of infarction. A dual-sensor (pressure and Doppler velocity) guidewire has an ability to evaluate microvascular damage quantitatively. We sought to investigate whether MVRI immediately after successful primary percutaneous coronary intervention (PCI) can predict the presence of MVO in patients with anterior AMI.
Methods: In 25 patients with TIMI grade 3 flow after primary PCI for a first anterior AMI, using a dual-sensor guidewire, MVRI was calculated as the ratio of mean distal pressure to average peak flow velocity during maximal hyperemia. With Ce-MRI, MVO was defined as hypodense regions within the hyperenhanced infarcted area. Myocardial necrosis was defined as transmural MI when delayed enhancement was extended to >75% of the thickness of at least 2 contiguous LV segments. According to the presence/absence of MVO, patients were divided into two groups (MVO group; n = 8, No-MVO group; n = 17).
Results: MVRI was strongly correlated with peak creatine kinase (CK)-MB (r = 0.657, p = 0.0003) and infarct size by MRI (r = 0.789, p < 0.0001). Patients with MVO had larger enzymatic infarct size by CK-MB (488 ± 158 IU/L vs. 258 ± 162 IU/L, p < 0.003), lager infarct size by ce-MRI (32.3 ± 8.9 % vs. 20.9 ± 11.5 %, p = 0.02), and higher MVRI (3.06 ± 0.62 mmHg•cm−1•s vs. 2.21 ± 0.85 mmHg•cm−1•s, p = 0.018). Moreover, the incidence of transmural MI was higher in the MVO group (62% vs. 12%, p < 0.02). In receiver-operating characteristic analysis, the best cut-off value of MVRI for predicting the presence of MVO was determined as 3.14 mmHg•cm−1•s (sensitivity 63%, specificity 89%).
Conclusions: MVRI immediately after primary PCI is a useful predictor for the presence of MVO in patients with reperfused MI. Our findings may suggest that in patients with high microvascular resistance, it is necessary to think about the adjunctive pharmacologic strategies for microvascular protection such as nicorandil to primary PCI.
- Coronary microcirculation
- Intravascular ultrasound/Doppler
- Myocardial infarction, STEMI
- Magnetic resonance imaging
- © 2010 by American Heart Association, Inc.