October 5, 2009
By Lisa Cowan Ph.D. and Asher Kimchi M.D.
Capa-Instanbul, Turkey – The relationship between infarct size and mortality is well known after STEMI, and a reduction in infarct size promises a substantial prognostic benefit. Murat Sezer, MD et al from Istanbul University in Capa-Istanbul, Turkey investigated if improvements in microvascular perfusion, measured by late phase infarct size and left ventricular volume and function, were obtainable with low dose adjuvant intracoronary streptokinase treatments given immediately after percutaneous coronary intervention. Their results, published in the September 15, 2009 issue of the Journal of the American College of Cardiology, showed that low-dose intracoronary streptokinase (ICSK) given immediately after primary percutaneous coronary intervention preserves left ventricular volumes and functions as well as significantly limits long-term infarct size.
Patients within the first 12 hours of STEMI undergoing primary percutaneous coronary intervention (PCI) were randomized to no additional therapy (n = 44) or ICSK, 250kU (n = 51). Patients with a history of prior myocardial infarction, thrombolysis in myocardial infarction (TIMI) flow grade 2 or 3 at infarct-related artery, culprit lesion in a saphenous vein graft, or left bundle branch block were excluded from this study. Ninety-five patients were enrolled in the trial between October 2004 and August 2007 and there was no significant difference between the control and ICSK groups regarding demographic, clinical, and angiographic characteristics; however, the mean age was lower and the pain-to-balloon time was longer in the ICSK group.
Patients in both the ICSK and control groups were treated with stent placement in the infarct-related artery after balloon dilation, 300 mg of aspirin, a loading dose of 600 mg clopidogrel, intracoronary unfractionated heparin (100 U/kg), tirofiban as a bolus (0.1 mg/kg in 3 min) and continuous infusion of 0.15 mg/kg/min for 12 hours. A femoral approach was used for invasive procedures. In addition, the ICSK group received 250kU of streptokinase diluted with 20 mL saline infused through the guiding catheter within 3 minutes.
On the second day after PCI, all subjects were recatherized to evaluate microvascular function. The ICSK group had significantly better microvascular perfusion than the control group, indicated by all perfusion parameters (IMR at second day (U): 19.9 ± 7.6 in ICSK group compared to 33.5 ± 13.3 in control group; CFP at second day: 2.7 ± 1.0 in ICKS group compared to 1.7 ± 0.7 in control group, etc.). There was no difference between the two groups, however, with respect to percent resolution of ST-segment deviation 90 minutes after primary PCI. Long term results of this study were also encouraging in that SPECT imaging at 6.2 ± 1.7 months showed significantly smaller infarct size in the ICSK group than in the control group (22.7% vs. 32.9%, p = 0.003, adjusted).
The study concluded that low-dose ICSK administered immediately after primary PCI improves microvascular perfusion, decreases long-term infarct size, and improves LV volume and function.
Authors: Murat Sezer, MD; Arif Cimen, MD; Emre Aslanger, MD; Ali Elitok, MD; Berrin Umman, MD; Yehra Bugra, MD; Ebru Yormaz, MD; Cuneyt Turkmen, MD; Isil Adalet, MD; Yilmaz Nisanci, MD; Sabahattin Umman, MD