Abstract 2855: Preceding Thrombolysis with Low-dose Mutant Tissue-type Plasminogen Activator Followed by Coronary Angioplasty in Acute Myocardial Infarction: PLANET Trial
In Japan, primary percutaneous coronary intervention (PCI) is a de facto standard reperfusion strategy for acute ST elevation myocardial infarction (STEMI) and thrombolysis is used in only 10% of pts who received reperfusion therapy. Nevertheless, thrombolysis-facilitated PCI has the theoretical potential to provide the speed of pharmacological reperfusion with the more complete and sustained reperfusion by PCI. Therefore, even in Japan, where primary PCI is predominantly performed, clinical benefit from combining pharmacologic and mechanical reperfusion for STEMI should be determined. PLANET Trial is a cluster-randomized multi-center trial comparing thrombolysis-facilitated PCI to primary PCI for acute STEMI (<12h onset). Primary endpoint was LVEF at 6 mo and secondary endpoints included regional LV function at 6 mo, infarct size, ST resolution, and myocardial blush grade, as well as incidence of bleeding complications. A total of 600 pts were enrolled. Baseline characteristics did not differ between the two arms. Because the protocol compelled to perform immediate PCI if % diameter stenosis of the culprit lesion exceeded 50%, PCI was conducted in 89.6% in facilitated PCI arm and 90.4% in primary PCI arm. Door to needle time in facilitated PCI arm was 30 min, and door to balloon time in primary PCI arm was 66 min. Thrombolysis facilitation with a bolus of half-dose mutant tPA (Pamiteplase or Monteplase) increased TIMI 3 flow restoration at the first angiogram (28.6% vs. 12.1%, p<0.05), while no increase in major bleeding complications (0.4% vs. 0.3%, p=NS). Final TIMI 3 flow was achieved in 91.1% at median of 204 min from the onset in facilitated PCI arm, and 91.0% in primary PCI arm at median of 216 min. No advantages for thrombolysis-facilitation were obtained over primary PCI in terms of global and regional LV function at follow-up or acute markers of tissue perfusion.
Conclusions: Time advantage (36 min) for thrombolysis-facilitation in the present study might be too small to elucidate significant functional and clinical benefit. “Time is muscle” should be further determined in the setting of pre-hospital facilitation, especially in situation when door to balloon time is expected to be significantly delayed.