Impact of QRS Duration on Non–ST-Segment Elevation Myocardial Infarction (from a National Registry)

QRS duration (QRSd) is ill-defined and under-researched as a prognosticator in patients with non-ST-segment myocardial infarction (NSTEMI). We analyzed 240,866 adult (≥18 years) hospitalizations with non-ST-segment elevation myocardial infarction using data from the United Kingdom Myocardial Infarction National Audit Project. Clinical characteristics and all-cause in-hospital mortality were analyzed according to QRSd, with 38,023 patients presenting with a QRSd >120 ms and 202,842 patients with a QRSd <120 ms. Patients with a QRSd >120 ms were more frequently older (median age of 79 years vs 71 years, p <0.001), and of white ethnicity (93% vs 91%, p <0.001). Patients with a QRSd <120 ms had higher frequency of use of aspirin (97% vs 95%, p <0.001), P2Y12 inhibitor (93% vs 89%, p <0.001), angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (82% vs 81%, p <0.001) and β blockers (83% vs 78%, p <0.001). Invasive management strategies were more likely to be used in patients with QRSd <120 ms including invasive coronary angiography (72% vs 54%, p <0.001), percutaneous coronary intervention (46% vs 33%, p <0.001) and coronary artery bypass graft surgery (8% vs 6%, p <0.001). In a propensity score matching analysis, there were no differences between the 2 groups in the adjusted rates of in-hospital all-cause mortality (odds ratio 0.94, 95% confidence interval 0.86 to 1.01) or major adverse cardiac events (odds ratio 0.94, 95% confidence interval 0.85 to 1.02) during the index admission. In conclusion, prolonged QRSd >120 ms in the context of non-ST-segment myocardial infarction is not associated with worse in-hospital mortality or the outcomes of major adverse cardiac events.