74 year-old male with hypertension, dyslipidemia and tobacco use, was presented with acute chest pain onset for 6 hours at the primary rural hospital.  Blood pressure was 130 / 72 mmHg. Heart rate was 82 beat per minute. Respiratory rate was 20 per minute.  Neither sign of heart failure nor neurological deficit were present.  

ECG shown atrial flutter with ST elevation at lead II, III and AVF with ST depression at V2 to V5. The diagnosis was ST elevation myocardial infarction infero-posterior wall.  The patient was referred to my PCI-center hospital for primary PCI strategy (referral time was 3 hours because of long distance).

The primary PCI procedure was started with Judkin right guiding catheter for right coronary artery (RCA) angiogram and plan for PCI. The RCA finding was shown with 100 % thrombotic occlusion since ostial RCA, PCI procedure was immediately done without left coronary angiogram. 

Guiding catheter was Judkin right (JR) 3.5 / 7 French. Guidewire with microcatheter was passed into RCA and confirmed with contrast injection via microcatheter. Massive thrombus along RCA was    presence. The first strategy, aspiration thrombectomy was performed for 3 times, but the RCA flow was not good because of massive thrombus.  The second strategy was low pressure balloon   dilatation with semi-compliant balloon 2.5 / 15 mm. for 4 - 6 atm, but the result was poor.  The next strategy was intracoronary thrombolysis (Alteplase), started with 5 mg via JR guiding catheter, after that no reflow and severe bradycardia were happening, thus internal temporary pacemaker was inserted.  The next step was used intracoronary Alteplase administered via aspiration thrombectomy catheter with Guidezilla assist because the JR guiding was not had backup support.  The Alteplase injection via aspiration thrombectomy  catheter was  successful (dose 5 mg, interval 5 minutes, total 2 doses).  The cine was shown the thrombus was nearly disappeared with TIMI 3 flow.  Then, semi-compliant balloon 2.5 / 15 mm was dilated at mid to ostial RCA.  The drug eluting stents were placed with 3.0 / 38 mm and 3.5 / 23 mm from mid to ostial RCA, retrogradely overlapped. Final angiogram shown final TIMI 3 flow. Intra-aortic balloon pump was inserted for hemodynamic support. 

STEMI with large thrombus burden was associated with poor prognosis, including procedural failure, abrupt vessel closure, recurrent myocardial infarction and death.  There were   many methods to reduce the thrombus load of patients with STEMI, such as distal protection device, thrombus aspiration, and glycoprotein IIb/IIIa antagonists, etc.  This case was  shown about the administration of low dose intracoronary thrombolysis strategy was significantly reduced residual thrombus after manual aspiration resulted in thrombus grade reduction, improved epicardial flow and tissue-level perfusion by dissolving thrombi at microvascular level. This strategy was safe without major bleeding complication.