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Clinical research

Pre-infarction angina predicts thrombus burden in patients admitted for ST-segment elevation myocardial infarction

Aims: In patients with ST-elevation myocardial infarction (STEMI), high thrombotic burden, subsequent distal embolisation and myocardial no-reflow remain a large obstacle that may negate the benefits of urgent coronary revascularisation. We aimed at assessing the predictors of: 1) thrombus grade in patients undergoing primary percutaneous coronary intervention (PPCI) and 2) infarct size, in order to optimise therapy to reduce thrombus burden.

Methods and results: One-hundred and fifty-three consecutive patients presenting with STEMI and undergoing PPCI were included. Thrombus was evaluated by angiography and scored according to the TIMI study group score. Next, patients were categorised into two groups that had either high thrombus grade (HTG; score 4-5) or low thrombus grade (LTG; score 1-3). We evaluated predictors of angiographic thrombus grade among a number of clinical, angiographic and laboratory data. We also assessed infarct size and scintigraphic left ventricular ejection fraction (LVEF) at three months in both patient groups. Ninety-four patients (58±11 years; 75% males) presented with HTG, whereas 59 patients (58±12 years; 78% males) presented with LTG. Pre-infarction angina (PIA) was more frequently encountered in the LTG group than in the HTG group (25% vs. 10%, p=0.009). Pre-procedural TIMI flow was significantly lower in the HTG group (p<0.001), and thrombosuction was more frequently applied in the HTG group (p<0.001). Absence of PIA (OR=0.29, 95% CI=0.11-0.75, p=0.01) and proximal culprit lesion (OR=2.10, 95% CI=1.02-4.36, p=0.04) were the only independent predictors of HTG. HTG proved an independent predictor of higher peak levels of creatine kinase (CK) (p<0.001) and troponin T (p<0.001), as well as lower LVEF (p=0.05) along with male gender and absence of prior statin therapy.

Conclusions: Absence of PIA and proximal culprit lesions are associated with higher thrombus grade. Higher thrombus grade is associated with larger infarct size and slightly worse LV function. This may have clinical implications in planning strategies, particularly regarding pharmacotherapy, that aim to decrease thrombus burden prior to stent implantation.

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