Myocardial 'no-reflow'--diagnosis, pathophysiology and treatment.
In acute ST-segment elevation myocardial infarction (STEMI), improvement in reperfusion strategies has contributed to improvement in mortality. Nonetheless up to 40-50% of patients who achieve satisfactory epicardial patency do not necessarily achieve patency at the coronary microvascular level, a condition referred to as the 'no-reflow' phenomenon. The 'no-reflow' phenomenon is associated with a worse prognosis at follow up. The pathogenic mechanisms underlying the 'no-reflow' phenomenon is complex and dynamic. This includes a variable combination of mechanisms including distal atherothrombotic embolisation, ischaemic injury, reperfusion injury and heightened susceptibility of coronary microcirculation to injury. Accurate detection of 'no-reflow' is crucial because it is independently associated with adverse ventricular remodelling and patient prognosis. The diagnosis of 'no-reflow' can be made using angiography, electrocardiography, nuclear scintigraphy, myocardial contrast echocardiography or cardiovascular magnetic resonance (CMR). Despite our improved understanding on the pathogenesis and diagnosis of 'no-reflow', the treatment of 'no-reflow' remains the 'Achilles heel' in the treatment of patients with acute myocardial infarction. Several therapeutic strategies have been tested for the prevention and treatment of 'no-reflow', however none have been associated with improvement in clinical outcomes. Therefore there exists a need for 'in-lab' tools that will be able to aid early identification of patients at increased risk of 'no-reflow'. This may enable patients at heightened risk of 'no-reflow' to be treated with the most appropriate individualised treatment early. We review the pathogenic mechanisms and diagnostic techniques of the 'no-reflow' phenomenon as well as the prevention and treatment strategies of the candidate mechanisms.
Cardiovascular Research Centre, Royal Adelaide Hospital & Discipline of Medicine, University of Adelaide, Adelaide, Australia.
Dennis T L
DT
Wong
Rishi
R
Puri
James D
JD
Richardson
Matthew I
MI
Worthley
Stephen G
SG
Worthley
D000818:Animals; D004562:Electrocardiography / Q000379:methods; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D009203:Myocardial Infarction / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy; D015425:Myocardial Reperfusion / Q000379:methods; D054318:No-Reflow Phenomenon / Q000175:diagnosis* / Q000503:physiopathology* / Q000628:therapy; D016896:Treatment Outcome
Cardiac MRI; Microvascular dysfunction; Myocardial infarction; No-reflow; STEMI; TMPG