Related Experiment Video
Updated: Jul 7, 2026
Digital PCR for Quantifying Circulating MicroRNAs in Acute Myocardial Infarction and Cardiovascular Disease
Published on: July 3, 2018
Predictive value of the index of microcirculatory resistance in patients with ST-segment elevation myocardial
William F Fearon1, Maulik Shah, Martin Ng
1Division of Cardiovascular Medicine, Stanford University Medical Center, Stanford, California 94305, USA. wfearon@stanford.edu
Insights
The index of microcirculatory resistance (IMR) better predicts microvascular damage after ST-segment elevation myocardial infarction (STEMI) compared to standard methods. IMR is a strong indicator of both acute damage and short-term prognosis following primary percutaneous coronary intervention.
Area of Science:
- Cardiology
- Interventional Cardiology
- Microvascular Physiology
Background:
- Microvascular damage significantly impacts prognosis in ST-segment elevation myocardial infarction (STEMI) patients, even after successful epicardial reperfusion.
- Assessing microvascular status in STEMI remains a clinical challenge.
Purpose of the Study:
- To evaluate the predictive capability of the index of microcirculatory resistance (IMR) in STEMI patients undergoing primary percutaneous coronary intervention (PCI).
Main Methods:
- IMR was measured using a pressure sensor/thermistor-tipped guidewire in 29 STEMI patients post-primary PCI.
- Additional assessments included Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade, TIMI frame count, coronary flow reserve, and ST-segment resolution.
Main Results:
- IMR strongly correlated with peak creatinine kinase (CK) levels (R = 0.61, p = 0.0005) and 3-month wall motion score (WMS) (R = 0.59, p = 0.002), outperforming other microvascular measures.
- Patients with IMR above the median (32 U) exhibited significantly higher peak CK and worse 3-month WMS.
- Multivariate analysis identified IMR as the strongest predictor of peak CK and 3-month WMS, and the sole significant predictor of left ventricular function recovery.
Conclusions:
- The index of microcirculatory resistance (IMR) demonstrates superior predictive value for microvascular damage in STEMI patients compared to conventional methods.
- IMR provides valuable acute and short-term prognostic information following primary PCI for STEMI.
Objectives:
The objective of this study is to evaluate the predictive value of the index of microcirculatory resistance (IMR) in patients undergoing primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI).
Background:
Despite adequate epicardial artery reperfusion, a number of patients with STEMI have a poor prognosis because of microvascular damage. Assessing the status of the microvasculature in this setting remains challenging.
Methods:
In 29 patients after primary PCI for STEMI, IMR was measured with a pressure sensor/thermistor-tipped guidewire. The Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade, TIMI frame count, coronary flow reserve, and ST-segment resolution were also recorded.
Results:
The IMR correlated significantly with the peak creatinine kinase (CK) (R = 0.61, p = 0.0005) while the other measures of microvascular dysfunction did not. In patients with an IMR greater than the median value of 32 U, the peak CK was significantly higher compared with those having values
Conclusions:
Compared to standard measures, IMR appears to be a better predictor of microvascular damage after STEMI, both acutely and in short term follow-up.
