How does coronary stent implantation impact on the status of the microcirculation during primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction?

Abstract

AimsPrimary percutaneous coronary intervention (PPCI) is the optimal treatment for patients presenting with ST-elevation myocardial infarction (STEMI). An elevated index of microcirculatory resistance (IMR) reflects microvascular function and when measured after PPCI, it can predict an adverse clinical outcome. We measured coronary microvascular function in STEMI patients and compared sequential changes before and after stent implantation.Methods and resultsIn 85 STEMI patients, fractional flow reserve, coronary flow reserve, and IMR were measured using a pressure wire (Certus, St Jude Medical, St Paul, MN, USA) immediately before and after stent implantation. Stenting significantly improved all of the measured parameters of coronary physiology including IMR from 67.7 [interquartile range (IQR): 56.2–95.8] to 36.7 (IQR: 22.7–59.5), P < 0.001. However, after stenting, IMR remained elevated (>40) in 28 (32.9%) patients. In 15 of these patients (17.6% of the cohort), only a partial reduction in IMR occurred and these patients were more likely to be late presenters (pain to wire time >6 h). The extent of jeopardized myocardium [standardized beta: −0.26 (IMR unit/Bypass Angioplasty Revascularization Investigation score unit), P: 0.009] and pre-stenting IMR [standardized beta: −0.34 (IMR unit), P: 0.001] predicted a reduction in IMR after stenting (ΔIMR = post-stenting IMR − pre-stenting IMR), whereas thrombotic burden [standardized beta: 0.24 (IMR unit/thrombus score unit), P: 0.01] and deployed stent volume [standardized beta: 0.26 (IMR unit/mm3 of stent), P: 0.01] were associated with a potentially deleterious increase in IMR.ConclusionImproved perfusion of the myocardium by stent deployment during PPCI is not universal. The causes of impaired microvascular function at the completion of PPCI treatment are heterogeneous, but can reflect a later clinical presentation and/or the location and extent of the thrombotic burden.

Index of Microcirculatory Resistance at the Time of Primary Percutaneous Coronary Intervention Predicts Early Cardiac Complications: Insights From the OxAMI (Oxford Study in Acute Myocardial Infarction) Cohort

“…10/H0408/24) 13, 14, 15, 16. Witnessed verbal assent was obtained from eligible patients after coronary reperfusion in the cardiac catheterization laboratory, and written informed consent was obtained on the ICU, in accordance with the principles of the Declaration of Helsinki.…”

Thrombus Aspiration, from “Heart to Soul”

“…De Maria et al showed that 60% of patients presented with a pre-stenting index of microcirculatory resistance (IMR) higher than 40, suggesting the presence of pre-procedural MVO. 31 In this group, the total ischemic time was longer, infarct size measured by the troponin test was larger, and more patients had a TIMI flow 0 at presentation. Onethird of patients had evidence of impaired microvascular function after a revascularization procedure with an IMR of >40 after stent implantation.…”

Role of deferred stenting in patients with ST elevation myocardial infarction treated with primary percutaneous coronary intervention: A systematic review and meta‐analysis

“…PPCI with stenting is the conventional gold standard treatment for patients with STEMI, but nearly one third of patients experience suboptimal myocardial reperfusion after stenting of the epicardial coronary segment. 29 Such a condition is well known as slow/no reflow and microvascular impairment is recognized as the pathophysiological mechanism. Stenting has been identified as a procedural step possibly associated with most of DE of athero-thrombotic debris thus contributing to the majority of the microvascular injury.…”

“…This is particularly relevant if considered that thrombotic burden is well recognized as an important risk factor for post-stenting microvascular injury in STEMI. 29 For this reason deferred stenting is anticipated to be effective mainly in case of large thrombotic burden which probably should be an inclusion criterion in future studies specifically designed to address the benefit of this approach. 11 However, each of the three RCTs available on this topic failed to address this important aspect.…”

“…In this context, the index of microcirculatory resistance has been suggested as a potential parameter to identify those STEMI patients with a higher likelihood of having a suboptimal response to stenting. 29 This novel, readily available parameter has an additional predictive value when measured before stenting and combined with clinical (age) and angiographic (thrombus score) variables to constitute the ATI score. This stratification tool has been validated to predict a suboptimal post-PPCI index of microcirculatory resistance in STEMI patients, and it could be adopted to identify STEMI patients who may benefit from a deferred stenting approach.…”