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EuroPCR 2017: Microcirculatory resistance could “have an edge in risk stratification over everything else”

This Hot Line Late-Breaking Trial session focused on the treatment of ST-elevation myocardial infarction (STEMI) patients. Covering ground on everything from bivalirudin infusion to cooling therapy, the session offered active participants a comprehensive update on the latest research in the area, including results described by chairperson Peter Jüni as potentially having “an edge over everything else” in the field of risk stratification.

Microcirculatory resistance could “have an edge in risk stratification over everything else”

The first data presented came from the BIVAL study of bivalirudin infusion for ventricular infarction limitation, which compared bivalirudin with standard heparin treatment. Robert-Jan Van Geuns gave a round-up of the trial, which was stopped for expected futility after interim analysis. The trial found “no significant reduction in infarct size” between the groups treated by each method, even though bivalirudin “completely inhibited thrombin generation within 10 minutes of completion of post-primary percutaneous coronary intervention (PPCI),” while unfractionated heparin failed to stop a small increase in thrombin generation. “A potentially hypothesis-generating observation of improved microvascular circulation could suggest further research,” R. J. Geuns observed.

A high proportion of the subsequent presentations discussed observational data, including Davide D’Andrea’s talk on a prospective, multicentre registry looking at an amphillimus-eluting stent and acute myocardial infarction, and Mamas Mamas’ presentation of one-year data from the e-ULTIMASTER registry analysing complete vs. incomplete revascularisation in STEMI patients with multivessel disease. D’Andrea’s data from a southern Italian population suggested safety and efficacy of Cre8’s amphilimus-eluting device, in agreement with previous research on the topic.

Much of the discussion following these talks focused on the pros and cons of registry data. Commenting on the limitations of D’Andrea’s results, audience member Anthony Gershlick said, “It is interesting that this is one of the few registry studies that actually supports the randomised controlled trial [of the device]. But, that clearly does not get away from the fact that this is a registry study… we will not know the answer to the question until we have an appropriately-sized, appropriately-powered randomised trial.” Responding, P. Jüni agreed, “There is some worth to registry data, but the problem is that we tend to over-interpret the results.

Mamas’ results found that “a complete revascularisation approach is associated with trends towards lower rates of adverse events at one year.” Mamas’ registry followed patients using the Ultimaster stent from Terumo. Mamas, whose data came from an “allcomers” registry, defended this study design as “half-way” between the strict selection of a randomised controlled trial and the lack of loose selection criteria of larger, national registries.

Another study of the session came from Kharbanda Rajesh, who presented the results of the Oxford Acute Myocardial Infarction cohort, who had undergone Index of Microcirculatory Resistance (IMR) measurement at the end of PPCI. K. Rajesh and colleagues demonstrated that IMR can “outperform current guideline-recommended strategies for risk stratification used to identify a group of patients at low-risk of early complications.

This is looking downstream,” K. Rajesh responded. “This is giving us an impression of what is going on in microcirculation. In terms of the relationship to other physiological indices in primary angioplasty, well, I think the debate is still out. But, if we can use that one wire to both assess culprit vessel physiology and bystander physiology, we can make this a one-stop-shop and provide delineated pathways for lots of patients.