Clinical and Angiographic Predictors of Microvascular Dysfunction in ST-Segment Elevation Myocardial Infarction

Abstract

Purpose: We aimed to discover clinical and angiographic predictors of microvascular dysfunction using the index of microcirculatory resistance (IMR) in patients with ST-segment elevation myocardial infarction (STEMI).

Materials and methods: We enrolled 113 patients with STEMI (age, 56±11 years; 95 men) who underwent primary percutaneous coronary intervention (PCI). The IMR was measured with a pressure sensor/thermistor-tipped guidewire after primary PCI. The patients were divided into three groups based on IMR values: Low IMR [<18 U (12.9±2.6 U), n=38], Mid IMR [18-31 U (23.9±4.0 U), n=38], and High IMR [>31 U (48.1±17.1 U), n=37].

Results: The age of the Low IMR group was significantly lower than that of the Mid and High IMR groups. The door-to-balloon time was <90 minutes in all patients, and it was not significantly different between groups. Meanwhile, the symptom-onset-to-balloon time was significantly longer in the High IMR group, compared to the Mid and Low IMR groups (p<0.001). In the high IMR group, the culprit lesion was found in a proximal location significantly more often than in a non-proximal location (p=0.008). In multivariate regression analysis, age and symptom-onset-to-balloon time were independent determinants of a high IMR (p=0.013 and p=0.003, respectively).

Conclusion: Our data suggest that age and symptom-onset-to-balloon time might be the major predictors of microvascular dysfunction in STEMI patients with a door-to-balloon time of <90 minutes.

Keywords: Microvascular dysfunction; ST-segment elevation myocardial infarction; doorto-balloon time; index of microcirculatory resistance; symptom-onset-to-balloon time.

Fig. 1. Relations of age (A), CK peak (B), and symptom-onset-to-balloon time (C) to increasing IMR. Solid lines represent linear regression lines. IMR, index of microcirculatory resistance; CK, creatine kinase.

Fig. 2. Comparison of IMR according to clinical and angiographic factors. ^*The IMR of patients with symptom-onset-to-balloon time of >180 minutes was significantly higher than the IMR of those with a symptom-onset-to-balloon ≤180 minutes, ^†The IMR was significantly higher in proximal lesion than in non-proximal lesion, ^‡The IMR was significantly higher in initial TIMI 0/1 group, as compared initial TIMI 2/3. IMR, index of microcirculatory resistance; LAD, left anterior descending artery; LCX, left circumflex artery; RCA, right coronary artery; P, proximal location of culprit artery; NP, non-proximal location of culprit artery; TIMI, thrombolysis in myocardial infarction.