Abstract 4159: Intracoronary ECG Predicts Microvascular Dysfunction Evaluated by Myocardial Blush Grade and TIMI Myocardial Perfusion Grade in Primary Percutaneous Coronary Intervention
Introduction Despite achieving TIMI 3 flow in treatment of ST elevation myocardial infarction (STEMI) with primary percutaneous coronary intervention (PPCI), microvascular perfusion remains impaired in 30 – 40% of patients leading to larger infarct size and higher mortality. Intracoronary ECG (IC-ECG) is a simple and novel method to assess microvascular dysfunction at the time of PPCI with the potential to guide medical therapy.
Hypothesis We assessed the hypothesis that intracoronary ECG can predict microvascular dysfunction as evaluated by MBG and TMPG during PPCI.
Method Fifty-three consecutive patients (age 62±10 years; 79% male) presenting with STEMI (anterior 42%) had IC-ECG ST segment measurement before and after (5, 10, 15 mins) opening of infarct related artery following PPCI. The intracoronary unipolar ECG was acquired by connecting the proximal portion of the angioplasty guidewire to an ECG monitor with the distal portion situated in the distal infarct-related artery. Myocardial blush grade (MBG) and TIMI myocardial perfusion grade (TMPG) were assessed at the end of PCI. Surface 12 lead ECGs were performed at 60 –90 mins, 3, 6, 12, 18, 24 hrs after achieving TIMI 3 flow. Surface ECG was analysed by two methods: Sum of ST elevation in all leads and maximal single lead. Association between categorical variables was assessed by Chi Square with two tailed p<0.05 as significant.
Results Despite restoration of normal TIMI 3 flow in 87.4% of patients, only 19.7% achieved TMPG 3. Almost all patients (97.5%) who had >50% ST segment resolution at the end of PCI on IC-ECG, achieved TIMI 3 flow at end of PCI (p=0.006). IC-ECG ST segment resolution >50% at end of PCI was predictive of MBG 3 in 78% of cases (p=0.002) and TMPG 2 in 63% & TMPG 3 in 17% of cases (p=0.006). However, there were no significant correlations between early surface ECG resolution with MBG and TMPG.
Conclusion IC-ECG is a novel immediate “in-lab” predictor of microvascular dysfunction and has the potential to direct future therapies for the reduction of microvascular injury. Further studies with this novel index are now warranted.