(P042) THE INFLUENCE OF INFARCT RELATED BASELINE Q WAVES ON ECG METRICS OF REPERFUSION IN STEMI: INSIGHTS FROM THE VHR PRE-HOSPITAL STEMI REGISTRY

Background: Prior clinical trial data suggests the presence of baseline Q-waves in the distribution of STEMI surpasses time of symptom onset as a prognostic marker of adverse outcomes. Whether the choice of reperfusion strategy mitigates these risks remains unclear. Moreover, those without baseline Q-waves are more likely to have ‘fresh’ thrombus whereby fibrinolysis with a pharmacoinvasive (PI) strategy may be more effective in achieving timely reperfusion. Accordingly, we examined the association between absence or presence of infarct-related baseline Q waves on ST-segment resolution as a marker of reperfusion, comparing a PI strategy to primary PCI (pPCI).

METHODS AND RESULTS: 927 consecutive STEMI patients with serial ECGs available to evaluate reperfusion were reviewed in the pre-hospital VHR STEMI Registry (2017-2021). Table 1 shows the ECG characteristics according to the absence or presence of baseline Q waves and reperfusion strategy employed. In this cohort, 22% presented with baseline Q waves in the distribution of STEMI. Time from symptom onset to baseline ECG was short (median 86-89 minutes) in the pre-hospital setting and similar regardless of baseline Q waves. Those with baseline Q waves had significantly greater ST-elevation and deviation at baseline. Following tenecteplase in the PI arms, there was greater resolution of ST elevation (deviation) with lower residual ST-deviation in those without baseline Q waves. Following angiography, ST resolution (deviation) and residual ST deviation was better in patients without a baseline Q wave regardless of choice of reperfusion strategy. Patients who underwent a PI strategy had more ST segment resolution (deviation) and less residual ST deviation than pPCI patients and the PI patients without a baseline Q wave achieved the best ST-segment resolution overall.

Conclusion: In a prospective cohort of pre-hospital STEMI patients receiving timely reperfusion in the VHR STEMI Registry, baseline Q waves were associated with poorer ECG metrics of reperfusion than those without a baseline Q wave, Moreover, a PI strategy without baseline Q waves was associated with best myocardial perfusion as assessed by the ECG. Baseline Q waves deserves attention when selecting a reperfusion strategy in STEMI patients.