Importance of Tissue Perfusion in ST Segment Elevation Myocardial Infarction Patients Undergoing Reperfusion Strategies: Role of Adenosine

Abstract

SummaryHigh risk ST segment elevation myocardial infarction (STEMI) patients undergoing reperfusion therapy continue to exhibit significant morbidity and mortality due in part to myocardial reperfusion injury. Importantly, preclinical studies demonstrate that progressive microcirculatory failure (the "no-reflow" phenomenon) contributes significantly to myocardial reperfusion injury. Diagnostic techniques to measure tissue perfusion have validated this concept in humans, and it is now clear that abnormal tissue perfusion occurs frequently in STEMI patients undergoing reperfusion therapy. Moreover, because tissue perfusion correlates poorly with epicardial blood flow (TIMI flow grade), clinical studies show that tissue perfusion is an independent predictor of early and late mortality in STEMI patients and is associated with infarct size, ventricular function, CHF and ventricular arrhythmias. The mechanisms responsible for abnormal tissue perfusion are multifactorial and include both mechanical obstruction and vasoconstrictor humoral factors. Adenosine, an endogenous nucleoside, maintains microcirculatory flow following reperfusion by activating four well-characterized extracellular receptors. Because activation of adenosine receptors attenuates the mechanical and functional mechanisms leading to the "no reflow" phenomenon and activates other cardioprotective pathways as well, it is not surprising that both experimental and clinical studies show striking myocardial salvage with intravenous infusions of adenosine administered in the peri-reperfusion period. For example, a post hoc analysis of the AMISTAD II trial indicates a significant reduction in 1 and 6-month mortality in STEMI patients undergoing reperfusion therapy who are treated with adenosine within 3 hours of symptoms. In conclusion, adenosine's numerous cardioprotective effects, including attenuation of the "no-reflow" phenomenon, support its use in high risk STEMI undergoing reperfusion.

Effect of New Method of Intracoronary Adenosine Injection during Primary Percutaneous Coronary Intervention on Microvascular Reperfusion Injury - Clinical Outcome and 1-Year Follow-Up

“…The highest incidence of impaired tissue perfusion was observed in LAD occlusions and the frequency of this complication was independent of the method of reperfusion. Numerous studies have noted a marked discrepancy between epicardial blood flow and tissue perfusion, emphasizing that normalization of epicardial blood flow (TIMI 3) frequently did not result in adequate tissue perfusion (MBG 3) [9,25]. Studies have also demonstrated that tissue perfusion is an independent predictor of both early and late mortality.…”

“…Although TIMI flow grade and CTFC provide information regarding the patency of epicardial arteries, these methods do not assess local tissue perfusion. The MBG is relatively simple and available in all cath-labs with semiquantitative angiographic measurement of evaluating tissue perfusion and clinicians use this method more and more frequently nowadays [23,25]. Impaired tissue perfusion occurred in up to 44% of patients with ST segment elevation myocardial infarction [9].…”

“…Normal tissue perfusion is associated with a significant decrease in infarct size and preservation of ventricular function. Abnormal tissue perfusion correlated with abnormal left ventricular remodeling, congestive heart failure, ventricular arrhythmias and rupture [4,9,24,25,26]. …”

Impervious Coronary No-Reflow: A Case Study

“…Adenosine has been studied extensively for its vasodilatory effect when injected into the coronary arteries, and also its properties that result in inhibition of platelet aggregation and thromboemboli formation [13][14][15]. However, its short half-life, and potential side effect of atrioventricular nodal blockade and hypotension may limit its use and benefit [16].…”

Left ventricular functional recovery after intracoronary injection of autologous bone marrow-derived stem cells in patients with acute myocardial infarction: A dose–response pilot study

“…It also rapidly reverses the effect of numerous vasoconstrictors in the coronary circulation during PCI [9]. One aim of this pilot study was to assess if adenosine injection given at the time of cell administration for a subgroup of patients improved the efficacy of the cell therapy.…”