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Aims: The potential influence of lunar phases on the occurrence of myocardial infarction is still controversial. The purpose of the present study was to investigate the association of the lunar cycle on the occurrence of fatal and non-fatal myocardial infarction based on a myocardial infarction registry.Methods and results: We studied 15,985 patients consecutively hospitalised with an acute myocardial infarction (AMI) between 1 January 1985 and 31 December 2007 with a known date of symptom onset who were recruited from a population-based myocardial infarction registry. The exact hour of AMI onset was known for 9813 events. Poisson regression analysis was performed to examine the relation between the lunar cycle and the occurrence of AMI.There was no association between new moon, full moon, waning moon and waxing moon and the occurrence of AMI. However, we observed that the three days after a new moon may be significantly protective for the occurrence of AMI, rate ratio (RR) 0.94 (95% CI 0.91–0.98), and the day before a new moon had a slightly negative effect (RR 1.06, 95% CI 1.00–1.12). Stratified analysis did not reveal any susceptible subgroups.Conclusion: The moon phases did not show any apparent association with AMI occurrence. However, there might be a ‘cardioprotective’ time three days after a new moon.

An increased number of hospital admissions for ischemic heart disease has been linked to ambient particles in time-series analyses. Strenuous exertion has been suggested to be a trigger of myocardial infarction in previous studies. We examine here the interaction between environmental factors and strenuous exercise. Cases of age 25 to 74 years were recruited from the Coronary Event Registry in Augsburg, Southern Germany from February 1999 through July 2001. In personal interviews, detailed information was collected on activities and location within 4 days preceding the onset of myocardial infarction. Fine particle mass (diameter below 2.5 µm (PM2.5)) was measured at 1 hour intervals. Temperature was recorded continuously at a central site. The association of strenuous exertion, being outside and 24 hour mean temperature with the onset of myocardial infarction (MI) was assessed using conditional logistic regression methods. the hour 0 and 1 before the MI were defined as case periods and the 24–25, 26–27 to 94–95 hours were defined as control periods, controlling for hour of day. Interactions of the individual exposures were tested and an effect modification due to temperature conditions or PM2.5 concentration was tested by stratification in low vs. normal to high temperature (cut-point: daily mean temp < 5 C on 3 or more of 4 previous days) and high versus normal to low air pollution exposure (cut-point: daily mean PM2.5 >14.5µg/m3 on 3 or more of 4 previous days). Of 906 interviewed cases with confirmed MI, 641 (70 age 55 years, 76 male) had valid time of onset and diary data, and spent most of the relevant time within the study area, i.e. they were eligible for the case-crossover analyses. The average of daily PM2.5 concentrations was 12.6 µg/m3, ranging from 3 to 52 µg/m3. Mean temperature was 10.8 C (minimum–12 C, maximum 27.3 C). The correlation of both was low (spearman's r = 0.05). Strenuous exertion 0 to 1 hours before an MI was associated with a seven fold risk (odds ratio (OR): 7.03; 95 confidence interval (CI): 4.51 to 11.0) and being outdoors during that period was associated with a twofold risk (OR: 2.24; CI: 1.72 to 2.91). Strenous activity outside was associated with a large odds ratio (OR: 16.35; CI: 9.72 to 27.51) which was significantly larger than the risk estimates for strenuous activity inside (OR: 1.49; CI: 0.66 to 3.35) or being outside without strenuous activity (OR: 1.47; CI: 1.08 to 2.00). No associations were observed between same day temperature and the MI onset. The risk of an MI shortly after outdoor strenuous activity was significantly higher on cold days (OR: 42.5; CI: 9.82 to 183.90) than on other days (OR: 13.8; CI: 7.84 to 24.25). In an air-polluted period the effect of being strenuously active inside as well as outside was (not significantly) higher than on less polluted days. The results suggest that adverse environmental conditions have an impact on the triggering effect of strenuous exertion not only if the activity is performed outside, but also if it is done indoors. funded by: Health Effect Institute, Research Agreement No. 98/1

Ambient air pollution has been associated with increased number of hospital admissions for cardiovascular disease. The HEAPSS project (Health Effects of Ambient Pollution in Susceptible Subpopulations) was designed to study the impact of ambient air pollution on first myocardial infarctions in 5 European cities Augsburg, Germany, Barcelona, Spain, Helsinki, Finland, Rome, Italy, Stockholm, Sweden. In the time periods between 1994 to 2000 incident cases of myocardial infarctions are being collected at each location. A follow-up for re-admission to cardiovascular disease or mortality was conducted until 2000. Two separate approaches for analyses are planned. Firstly, the association between ambient air pollution and the incidence of the first MI will be studied. The proposed analyses will use poisson regression models analysing the daily number of first MI cases as outcome variable. In addition, case-crossover analyses will be conducted using the stratified control sampling method. This will be used to particualrly look at susceptible subgroups such as diabetics. Secondly, re-admissions to the hospital due to cardiovascular diseases and mortlaity will be analysed. Here three different analytical approaches will be considered. Poisson regression analyses considering the number of MI survivors at risk will built on the time-series analyses expiereince. However, the numbers might be very small in some locations. Therefore, the methods of the case-crossover analyses as well as cohort analyses will be applied to the data. The goal of the analyses is to evaluate whether patients with myocardial infarctions have a high risk of a second fatal event at days with high air pollution. Preliminary analyses of the Rome data comparing Poisson regression analyses adjusting for trend, season, weather and calendar effects with stratified case-crossover analyses suggested that similar effect estimates were obtained. The standard errors were slightly larger for the case-crossover analyses than the time-series analyses. Lagstructures were explored and no evidence for longer lags were found, which potentially could have impaired the control selection in the case-crossover analyses. For the incident cases, the case-crossover analyses provide an alternative to efficiently address the effects in subgroups. These methods might therefore be also adopted for the follow-up analyses as the number of cases are substantially lower in these datasets.