LETTER TO THE EDITOR: REPLY
Reply
J. P. S. Henriques, MD*,
A. P. Haasdijk, MD*,
F. Zijlstra, MD, PhD* Zwolle Myocardial Infarction Study Group
* Department of Cardiology,Isala Klinieken, locatie Weezenlanden,Groot Wezenland 20,8011 JW Zwolle,The Netherlands,
v.derks{at}diagram-zwolle.nl
We appreciate Dr. Haas's as well as Dr. Steg's and their colleagues' interest and comments on our report concerning the different outcome of primary PCI patients treated during the day versus during the off-hours (evening and night) (1). Dr. Haas's comment is very interesting, as it would possibly explain the apparent difference in mortality from a more biological perspective. Depression affects the circadian variation of onset of acute myocardial infarction (MI) and predicts revascularization over a longer period of time (2–4), implying that biological factors may be involved. Unfortunately, we did not measure prospectively the mental state prior to onset of acute MI.
The question remains whether this difference in outcome is due to biological factors or to factors related to seeking and/or administering care (5). Before returning to this question, it is important to emphasize that the variation of onset of acute MI has been demonstrated previously. In the very large ISIS-2 trial, with >17,000 patients (6), there was a rise of onset of acute MI from 0600 h, which lasted until 1800 h, after which there was a fall in onset of acute MI until 0600 h. Our data are compatible with these findings. Therefore, the majority of patients with acute MI will be treated during the day (0800 to 1800 h). Circadian variation and different outcomes in patients with thrombolysis have been published and discussed in our study (1) and in the accompanying editorial (5). With respect to different coagulation states during the day, it is important to point out that we did not find a difference in TIMI-2 and -3 flow before angioplasty, suggesting that coagulation may not be an important factor. Heart failure also seems to occur more frequently during the night compared with during the day, suggesting a biological factor (7). However, the question "Is it biology or care?" has not yet been answered definitively. We, however, did not find a difference in the care delivered.
Dr. Steg and colleagues argue that there was no difference in outcome in their study (8), when off-hours were compared with routine day hours. Their cohort comprised only 288 patients, perhaps making the study underpowered to detect a difference. Furthermore, in Dr. Steg's study, off-hours also comprised day hours during the weekend. We only analyzed our data with respect to day and night as this seems a more biological division. Both the number of patients studied and the division used to analyze off-hours and routine hours may have influenced the outcome of Dr. Steg's study. We further analyzed whether this mortality difference was present in referred patients and nonreferred patients. In both referred and nonreferred patients, mortality was higher when treated between 1800 and 0800 h, compared with between 0800 and 1800 h. Mortality in referred patients was 2% versus 6% (p = 0.01) and in nonreferred patients 2% versus 3% (p = 0.37), respectively. The Breslow-Day test for heterogeneity was negative. Nevertheless, referral patterns may have affected our conclusions.
This underscores the need to restudy this issue in an even larger population.
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References
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- Zwolle Myocardial Infarction Study GroupHenriques JPS, Haasdijk AP, Zijlstra F. Outcome of primary angioplasty for acute myocardial infarction during routine duty hours versus during off-hours. J Am Coll Cardiol. 2003;41:2138–2142[Abstract/Free Full Text]
- Carney RM, Freedland KE, Jaffe AS. Altered circadian pattern of acute myocardial infarction in patients with depression. Coron Artery Dis. 1991;2:61–65
- Rozanski A, Blumenthal JA, Kaplan J. Impact of psychological factors on the pathogenesis of cardiovascular disease and the implications for therapy. Circulation. 1999;99:2192–2217[Abstract/Free Full Text]
- Sullivan MD, LaCroix AZ, Spertus JA, Hecht J, Russo J. Depression predicts revascularization procedures for 5 years after coronary angiography. Psychosom Med. 2003;65:229–236[Abstract/Free Full Text]
- Spencer FA, Becker RC. Circadian variations in acute myocardial infarction: patients or health care delivery? J Am Coll Cardiol. 2003;41:2143–2146[Free Full Text]
- ISIS-2 (Second International Study of Infarct Survival) Collaborative Group. Peak in the incidence of myocardial infarction: experience in the ISIS-2 trial. Eur Heart J. 1992;13:594–598[Abstract/Free Full Text]
- Mukamal KJ, Muller JE, Maclure M, Sherwood JB, Mittleman MA. Increased risk of congestive heart failure among infarctions with nighttime onset. Am Heart J. 2000;140:438–442[CrossRef][Medline]
- Garot PH, Juliard JM, Benamer H, Steg PG. Are the results of primary PTCA for acute myocardial infarction different during the "off" hours? Am J Cardiol. 1997;79:1527–1529[CrossRef][Medline]
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References