Primary PCI for acute myocardial infarction: clinical and angiographic features

Objectives. We sought to investigate the impact of circadian patterns in the onset of acute myocardial infarction on the practice of primary angioplasty. Background. A circadian variation in the time of onset of acute myocardial infarction with a peak in the morning hours has been described. Methods. We studied 1702 consecutive patients with acute ST segment elevation myocardial infarction treated with primary angioplasty. We observed circadian variation in frequency of symptom-onset, hospital admission, and first balloon inflation. Circadian patterns of symptom-onset, hospital admission and balloon inflation are similar. Results. A majority of patients have symptom-onset (53%), hospital admission (53%) and first balloon inflation (52%) during routine duty hours (08.00-18.00h). There were no differences in baseline clinical characteristics or treatment delays between routine duty hours and off-hours patients. Hospital admission between 08.00 and 18.00 was associated with an angioplasty failure rate of 3.8%, compared to 6.9% between 18.00 and 08.00, p<0.01. Thirty day mortality was 1.9% in patients with hospital admission between 08.00 and 18.00, compared to 4.2% in patients with hospital admission between 18.00 and 08.00, p<0.01. Conclusions. Circadian variations may have a profound effect on the practice of primary angioplasty. A majority of patients is treated during routine duty hours. Patients treated during off-hours have a higher incidence of failed angioplasty and consequently a worse clinical outcome, when compared to patients treated during routine duty hours.