Causes of Delay and Associated Mortality in Patients Transferred With ST-Segment–Elevation Myocardial Infarction
What is the frequency, magnitude, and clinical impact of specific delays in a standardized regional system designed for the rapid transfer of ST-segment elevation myocardial infarction (STEMI) patients for primary percutaneous coronary intervention (PCI) in a real-world population?
This was a prospective, observational study of 2,034 patients transferred for primary PCI at a single center as part of a regional STEMI system from March 2003 to December 2009. The authors used χ2 or Fisher exact tests to compare in-hospital, 30-day, and 1-year mortality in those with balloon times ≤120 minutes and those with times >120 minutes.
Despite long-distance transfers, 30.4% of patients (n = 613) were treated in ≤90 minutes and 65.7% (n = 1,324) were treated in ≤120 minutes. Delays occurred most frequently at the referral hospital (64.0%, n = 1,298), followed by the PCI center (15.7%, n = 317) and transport (12.6%, n = 255). For the referral hospital, the most common reasons for delay were awaiting transport (26.4%, n = 535) and emergency department delays (14.3%, n = 289). Diagnostic dilemmas (median, 95.5 minutes; 25th and 75th percentiles, 72-127 minutes) and nondiagnostic initial electrocardiograms (ECGs) (81 minutes; 64-110.5 minutes) led to delays of the greatest magnitude. Delays caused by cardiac arrest and/or cardiogenic shock had the highest in-hospital mortality (30.6%), in contrast with nondiagnostic initial ECGs, which despite long treatment delays, did not affect mortality (0%). Significant variation in both the magnitude and clinical impact of delays also occurred during the transport and PCI center segments.
The authors concluded that the clinical impact of specific delays in interhospital transfer for PCI varies according to the cause of the delay.
This study suggests that clinical outcomes vary significantly according to the reason for the delay, and that not all delays are STEMI system dependent. In this study, more than one third of the deaths from the entire cohort occurred in patients who developed cardiogenic shock and/or cardiac arrest before PCI. The vast majority of patients developed this complication before or shortly after their arrival to the referral hospital, indicating that the cardiac complication led to the delay rather than the delay contributing to the complication. These results have implications for the design of regional STEMI systems, the inclusion of transferred STEMI patients in core measures, and national guidelines for STEMI care.
Keywords: Shock, Cardiogenic, Myocardial Infarction, Hospital Mortality, Percutaneous Coronary Intervention
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