Diagnostic delays and cardiovascular mortality in left circumflex culprit ST-segment elevation myocardial infarction: a 16-year experience

ST-segment elevation myocardial infarction (STEMI) due to left circumflex artery (LCx) occlusion presents with a different phenotype than other culprit lesions. We assessed whether LCx culprits had different acute management patterns and short- and long-term outcomes. The prospective EVALFAST registry included all consecutive STEMI patients treated with primary percutaneous coronary intervention from June 2008 to November 2024. Process times, peak enzymes, left ventricular ejection fraction (LVEF), and cardiovascular (CV) mortality were compared between LCx and non-LCx culprits using multivariable generalized linear and Cox models. Among 1,205 patients, 166 (13.8%) had LCx culprit. LCx prolonged first medical contact-to-diagnosis by 6.7 min (p<0.001), peak CK-MB was higher (+48 U/L, p=0.004), yet LVEF was 5.8 percentage points higher (p<0.0001) vs. non-LCx. LCx showed increased 30-day CV mortality (adjusted HR 4.13; p=0.001). Among 30-day survivors, LCx demonstrated no increased 1-year mortality (HR 0.62; p=0.66) and trend toward better 5-year survival (HR 0.21; p=0.12). LCx culprit lesions in our fast-track STEMI network showed diagnostic delays, larger enzymatic infarcts despite preserved LVEF, and increased early CV mortality. This contrasts with favorable long-term outcomes among 30-day survivors, who demonstrated better prognosis than LAD and RCA survivors. • LCx STEMI: 6.7-min diagnostic delay in mature fast-track network • Larger enzymatic infarcts despite preserved LVEF in LCx culprits • Higher 30-day CV mortality with LCx vs non-LCx culprits • LCx 30-day survivors showed trend to better 5-year outcomes • Lower cardiac rehabilitation enrollment after LCx infarction