Hyperaemic microvascular resistance predicts clinical outcome and microvascular injury after myocardial infarction

Abstract

HMR measured immediately following percutaneous coronary intervention for AMI with a cut-off value of 3.0 mm Hg cm s, identifies patients with MVI who are at high risk of adverse clinical outcome. For this purpose, HMR is superior to CFR.

Reference invasive tests of microvascular injury in myocardial infarction

“…Alternatively, IMR would seem better disposed for use in real-world practice. The findings of de Waard et al 5 complement those of previously published studies 3 4 in a number of important ways. First, a broader range of MI types were included (ie, both STEMI (n=130) and non-STEMI (n=46) patients were analysed) with stable patients (without coronary artery disease) serving as a reference cohort.…”

“…De Waard et al 5 found that CFR <1.5 was predictive for the composite endpoint (death and hospitalisation for heart failure), HR: 3.5, 95% CI 1.1 to 10.8, but not for the separate components of death and heart failure hospitalisations. HMR ≥3.0 mm Hg·cm -1 -s was more strongly predictive for the composite endpoint, HR: 7.0, 95% CI 1.5 to 33.7, was an independent predictor for its individual components and remained independently associated with the composite outcome after adjustment for baseline and procedural characteristics.…”

“…In their Heart manuscript, de Waard et al 5 present their findings on hyperaemic microvascular resistance (HMR), compared with CFR, measured immediately after PCI for MI (n=176), as a predictor of clinical outcome and MVO (referred to as microvascular injury in their paper). HMR may be considered analogous to IMR, as they are both measures of microvascular resistance.…”

“…Indeed, in the current study, 8% of invasive measurements had to be excluded, due to poor Doppler flow signals, or iatrogenic coronary dissection in one patient. 5 Compared with IMR, Doppler guide wire measurements have a steeper learning curve, the measurements are technically challenging, the amount of time involved to acquire the data may be longer and in general the Doppler wire is more expensive than the wire that is used to measure IMR. For all of these reasons, HMR is currently a method used in research protocols rather than in routine practice.…”

Heartbeat: Age-related changes in the cardiac response to exercise

“…Early detection of microvascular dysfunction might allow additional interventions to restore myocardial blood flow and prevent long-term adverse outcomes. In a study of 176 AMI patients, de Waard and colleagues4 found that hyperaemic microvascular resistance (HMR) was superior to invasively measured coronary flow reserve (CFR) for detection of microvascular injury on subsequent cardiac magnetic resonance imaging and for prediction of the composite end point of death or hospitalisation for heart failure (which occurred in 10% of patients) (figure 3). …”