Failed reperfusion after thrombolytic therapy: recognition and management

Fragmented QRS predicts reperfusion failure and in-hospital mortality in ST-Elevation myocardial infarction: a systematic review and meta-analysis

Objective: Recent studies have shown that fragmented QRS (fQRS) is associated with unfavourable outcomes in STEMI patients. However, there is controversy amongst studies. We performed a systematic review and meta-analysis to explore the effect of fQRS on reperfusion failure and in-hospital mortality among this population.Methods: We searched the databases of MEDLINE and EMBASE from inception to October 2018. Included studies were published cohort studies of STEMI patients that underwent primary percutaneous coronary intervention (pPCI) and thrombolysis. Data from each study were combined using the random-effects model.Results: Ten studies from January 2011 to October 2018 (2753 patients, 1075 patients with fQRS), were included. The fQRS was associated with higher risk of reperfusion failure in pPCI when defined by ST-segment resolution (OR = 3.08, 95% CI = 1.27-7.46, p-value = .013) but not when defined by TIMI flow grade (pooled OR = 1.45, 95% CI = 0.83-2.54, p-value = .192). In thrombolysis, fQRS was associated with higher risk of reperfusion failure when defined by both ST-segment resolution (pooled OR = 4.35, 95% CI = 1.80-10.49, p-value = .001) and TIMI flow grade (OR = 3.70, 95% CI = 2.10-6.53, p-value < .001). The fQRS was also associated with an increased risk of in-hospital mortality in both pPCI (pooled OR = 4.41, 95% CI = 1.60-12.16, p-value = .004) and thrombolysis (pooled OR = 2.38, 95% CI = 1.06-5.35, p-value = .036).Conclusions: Our meta-analysis demonstrated that fQRS in STEMI patients was associated with reperfusion failure as well as in-hospital mortality.

Platelets synthesize large amounts of active plasminogen activator inhibitor 1

Previous studies have suggested that plasminogen activator inhibitor 1 (PAI-1) released from platelets convey resistance of platelet-rich blood clots to thrombolysis. However, the majority of PAI-1 in platelets is inactive and therefore its role in clot stabilization is unclear. Because platelets retain mRNA and capacity for synthesis of some proteins, we investigated if platelets can de novo synthesize PAI-1 with an active configuration. PAI-1 mRNA was quantified with real-time polymerase chain reaction and considerable amounts of PAI-1 mRNA were detected in all platelet samples. Over 24 hours, the amount of PAI-1 protein as determined by an enzyme-linked immunosorbent assay increased by 25% (P = .001). Metabolic radiolabeling with (35)S-methionine followed by immunoprecipitation confirmed an ongoing PAI-1 synthesis, which could be further stimulated by thrombin and inhibited by puromycin. The activity of the newly formed PAI-1 was investigated by incubating platelets in the presence of tissue-type plasminogen activator (tPA). This functional assay showed that the majority of the new protein was in an active configuration and could complex-bind tPA. Thus, there is a continuous production of large amounts of active PAI-1 in platelets, which could be a mechanism by which platelets contribute to stabilization of blood clots.