< Return

Circadian modulation of effectiveness in prehospital thrombolysis

Barneto Valero MC, Garmendia Leiza JR, Andrés De Llano JM, Corral Torres E , García de Buen JM, Blas de Blas AA

Departamento de Operaciones, SAMUR-Protección Civil, Madrid, Spain. Grupo de Investigación Reconocido de Cronobiología, Universidad de Valladolid, Valladolid, Spain. Subdirección General, SAMUR-Protección Civil, Madrid, Spain.

Objective: To study whether time of day influences the effectiveness of prehospital
thrombolysis in patients who have had acute myocardial infarction with ST-segment
elevation (STEMI).
Methods: Observational study of retrospective cohorts. We included patients
diagnosed with STEMI who received early application of prehospital thrombolytic
therapy. The main variable studied as an independent predictor of effectiveness was
the time of day the thrombolytic agent was administered; this variable was studied in
6-hour periods and 12-hour periods. Additional independent variables were patient
age and sex, onset of chest pain, duration of pain from onset until administration of
the thrombolytic agent, cardiovascular risk factors, and location of infarction. Data
were extracted from patient records and ambulance pre-alert calls in the next 24
Results: Two hundred six patients were studied. The 2 independent variables that
predicted the effectiveness of prehospital thrombolysis were administration of the
thrombolytic agent at a time of day within the period of greatest cardiovascular risk (6
AM to 12 noon) in comparison with the other time frames (12 midnight to 6 AM, 12
noon to 6 PM and 6 PM to midnight) (odds ratio [OR], 2.46; 95% CI, 1.30-4.64;
P=.005) and history of ischemic heart disease (OR, 5.30; 95% CI, 1.74-16.15; P=.003).
Conclusions: We found that circadian rhythm had a clinically significant effect on the
effectiveness of prehospital thrombolysis in STEMI patients. The effect was present
regardless of which thrombolytic agent was used. The greatest resistance to therapy
was observed in the morning hours between 6 AM and 12 noon. The response was
greater in the remaining time frames and greatest in the hours between noon and 6

Síguenos en:

Search the Journal

* Search for article from 1988 to present (from volume 1, number 0, 1988)