Reasons for reperfusion delay in ST-elevation myocardial infarction and their impact on mortality

Aims: The impact of reperfusion delay in ST-elevation myocardial infarction (STEMI) is well known. We aimed to describe the specific reasons for delay to primary percutaneous coronary intervention (pPCI), and their impact on mortality after adjusting for confounders, using the first-medical-contact-to-device (FMCTD) time to measure the delay.

Methods: Between January 2006 and December 2019, 2149 STEMI patients underwent pPCI at our centre. Delayed pPCI was defined as FMCTD > 90 min or > 120 min in the case of inter-hospital transfer. The causes of delay were classified as system-related (related to the network organization) or patient-related (related to the clinical condition of the patient). Primary outcome was 1-year all-cause mortality.

Results: The pPCI was timely in 69.9% of patients, delayed for system-related causes in 16.4% or for patient-related causes in 13.7%. Different patient-related causes induced variable median FMCTD time (from 114 min for technically difficult pPCI to 159 min for ECG and/or symptom resolution). By multivariable Cox-regression models, the main independent risk factors for mortality were delay due to comorbidities [hazard ratio (HR) 2.19 (1.22-3.91)], or hemodynamic instability [HR 2.05 (1.25-3.38)], after adjusting for Global Registry of Acute Coronary Events risk score tertiles and angiographic success. The difference in risk of mortality is maintained over the entire spectrum of time from symptom onset.

Conclusions: Different causes of delay had different impacts on mortality, generally more important than the length of the delay. Causes of delay such as hemodynamic instability and comorbidities should prompt specific programs of performance improvement. Timely pPCI maintains prognostic advantages after several hours from symptom onset, mandating prompt reperfusion also in late-presenter patients.