Beneficial effect of reperfusion therapy beyond the preservation of left ventricular function in patients with acute ST-segment elevation myocardial infarction

Growth differentiation factor 15 may protect the myocardium from no‑reflow by inhibiting the inflammatory‑like response that predominantly involves neutrophil infiltration

The aim of the current study was to investigate the time course of the expression of growth differentiation factor‑15 (GDF‑15) in rat ischemic myocardium with increasing durations of reperfusion, and to elucidate its physiopathological role in the no‑reflow phenomenon. Wistar rats were randomly divided into ischemia reperfusion (I/R) and sham groups, and myocardial I/R was established by ligation of the left anterior descending coronary artery for 1 h followed by reperfusion for 2, 4, 6, 12, 24 h and 7 days whilst rats in the sham group were subjected to a sham operation. The expression levels of GDF‑15 and ICAM‑1 were measured, in addition to myeloperoxidase (MPO) activity. The myocardial anatomical no‑reflow and infarction areas were assessed. The area at risk was not significantly different following various periods of reperfusion, while the infarct area and no‑reflow area were significantly greater following 6 h of reperfusion (P<0.05). The mRNA and protein expression levels of GDF‑15 were increased during the onset and development of no‑reflow, and peaked following 24 h of reperfusion. MPO activity was reduced with increasing reperfusion duration, while ICAM‑1 levels were increased. Hematoxylin and eosin staining demonstrated that myocardial neutrophil infiltration was significantly increased by I/R injury, in particular following 2, 4 and 6 h of reperfusion. GDF‑15 expression levels were negatively correlated with MPO activity (r=‑0.55, P<0.001), and the MPO activity was negatively correlated with the area of no‑reflow (r=‑0.46, P<0.01). By contrast, GDF‑15 was significantly positively correlated with ICAM‑1 levels (r=0.52, P<0.01), which additionally were demonstrated to be significantly positively associated with the size of the no‑reflow area (r=0.39, P<0.05). The current study demonstrated the time course effect of reperfusion on the expression of GDF‑15 in the myocardial I/R rat model, with the shorter reperfusion times (6 h) resulting in significant no‑reflow in ischemic myocardium. GDF‑15 may protect the I/R myocardium from no‑reflow by inhibiting the inflammatory‑like response, which involves neutrophil infiltration and transendothelial migration.

Early coronary revascularization improves 24h survival and neurological function after ischemic cardiac arrest. A randomized animal study

BACKGROUND

Survival after out-of-hospital cardiac arrest (OHCA) remains poor. Acute coronary obstruction is a major cause of OHCA. We hypothesize that early coronary reperfusion will improve 24h-survival and neurological outcomes.

METHODS

Total occlusion of the mid LAD was induced by balloon inflation in 27 pigs. After 5min, VF was induced and left untreated for 8min. If return of spontaneous circulation (ROSC) was achieved within 15min (21/27 animals) of cardiopulmonary resuscitation (CPR), animals were randomized to a total of either 45min (group A) or 4h (group B) of LAD occlusion. Animals without ROSC after 15min of CPR were classified as refractory VF (group C). In those pigs, CPR was continued up to 45min of total LAD occlusion at which point reperfusion was achieved. CPR was continued until ROSC or another 10min of CPR had been performed. Primary endpoints for groups A and B were 24-h survival and cerebral performance category (CPC). Primary endpoint for group C was ROSC before or after reperfusion.

RESULTS

Early compared to late reperfusion improved survival (10/11 versus 4/10, p=0.02), mean CPC (1.4±0.7 versus 2.5±0.6, p=0.017), LVEF (43±13 versus 32±9%, p=0.01), troponin I (37±28 versus 99±12, p=0.005) and CK-MB (11±4 versus 20.1±5, p=0.031) at 24-h after ROSC. ROSC was achieved in 4/6 animals only after reperfusion in group C.

CONCLUSIONS

Early reperfusion after ischemic cardiac arrest improved 24h survival rate and neurological function. In animals with refractory VF, reperfusion was necessary to achieve ROSC.