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Risk of death from heart attack varies according to when patients arrive at hospital, study finds

BMJ 2005; 331 doi: (Published 18 August 2005) Cite this as: BMJ 2005;331:422
  1. David Spurgeon
  1. Quebec

    Restoration of normal blood flow is delayed and risk of death is higher for some heart attack patients if they arrive at hospital between 5pm and 7am or on a weekend, a new study shows.

    This is the finding of a study from the US healthcare organisation Kaiser Permanente, headed by Dr. David J. Magid, Clinical Research Unit, Kaiser Permanente Denver. It looked at data on 68 439 patients with an electrocardiography finding known as an ST-segment elevation myocardial infarction who were treated with fibrinolytic drugs at 1015 hospitals across the country and 33 647 patients with the same electrocardiography finding who were treated with percutaneous coronary interventions (PCIs), such as angioplasty, at 421 hospitals across the country (JAMA 2005;294:803-12). The data covered the years 1999 to 2002

    “The shorter the time from symptom onset to treatment, the greater the survival benefit with either therapy,” say the authors.

    The researchers found that most patients in each group (68% in the fibrinolytic treatment group and 54% in the PCI group) were treated during off-hours. In the fibrinolytic treatment group the time from arrival at hospital to receiving the treatment was slightly longer in off-hours (34.3 minutes) than in regular hours (33.2 minutes). In the PCI group, in contrast, the time from arrival at hospital to receiving PCI was substantially longer during off-hours (116.1 minutes) than during regular hours (94.8 minutes).

    Guidelines recommend the time in which patients should receive PCI. Fewer patients met the recommended times in off-hours (26%) than in regular hours (47%). The percentage of patients whose time to treatment exceeded 120 minutes was much higher in off-hours (42%) than in regular hours (28%). The longer times in off-hours were due primarily to a longer interval between the electrocardiography being done and the patient's arrival at the catheterisation laboratory (70 minutes in off-hours and 49 minutes in regular hours). This pattern was consistent across all the sub-groups of hospital.

    The difference in mortality between the patients arriving in off-hours and those arriving in regular hours was reduced by 43% when researchers adjusted for differences in the time to reperfusion treatment, indicating that the higher mortality during off-hours was partly due to longer time to reperfusion. The researchers add that their study shows that delays to PCI in off-hours are common to all types of hospitals, including high volume PCI centres.

    “One way to improve the timeliness of PCI during off-hours would be to provide on-site staffing of the cardiac catheterisation laboratory around-the-clock,” write the authors. “However, the clinical benefits of providing [this] must be weighed against the extra cost … Another possible solution is to cross-train non-cardiac catheterisation laboratory staff to assist with PCI during off-hours. However, [such] benefits may not be realised unless rapid access to interventional cardiologists is also available.”

    Locating interventional cardiac care in regional centres would be another possibility: during off-hour periods patients would be taken to institutions with continuous staffing and that have short times from arrival at the hospital to catheterisationBut this would affect only patients who could be transported by emergency service vehicles, and the faster treatment times might be offset by the time of transportation to such hospitals.

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