ORIGINAL PAPER Weather-induced ischemia and arrhythmia in patients undergoing cardiac rehabilitation: another difference between men and women Alexandra Schneider & Angela Schuh & Friedrich-Karl Maetzel & Regina Rückerl & Susanne Breitner & Annette Peters Received: 26 June 2007 / Revised: 15 October 2007 / Accepted: 2 January 2008 / Published online: 29 January 2008 # ISB 2008 Abstract Given the accumulating evidence that people with underlying heart disease are a particularly vulnerable group for triggers like changing meteorological parameters, the objective of this longitudinal study was to analyze the influence of weather parameters on blood pressure, arrhyth- mia and ischemia in cardiovascular patients. A panel study with repeated measurements was conducted in a rehabili- tation clinic in Timmendorfer Strand (Baltic Sea, Germany) with 872 cardiovascular patients. Heart rate, blood pressure and electrocardiography changes were measured during repeated bicycle ergometries. Generalized Estimating Equa- tions were used for regression analyses of immediate, delayed and cumulative influences of the daily measured meteorological data. For men, a decrease in air temperature and in water vapor pressure doubled the risk of ST-segment depression during ergometry [odds ratio (OR) for 1 day delay: 1.88 (1.24; 2.83) for air temperature] with a delay of 1–2 days. For women, an increase of their heart rate before the start of the ergometry [same day: 4.36 beats/min (0.99; 7.74) for air temperature] and a 2- to 3-fold higher risk for ventricular ectopic beats [1 day delay: OR 2.43 (1.17; 5.05) for air temperature] was observed with an increase in temperature and water vapor pressure in almost all analyzed time-windows. The study indicates that meteorological parameters can induce changes in heart function which may lead to adverse cardiovascular events especially in susceptible, diseased individuals. The observed effect on ST-segment depression could be a link between the association of weather changes and cardiovascular morbid- ity and mortality. Keywords Epidemiology . Meteorological factors . Weather . Rehabilitation . Ergometry Introduction The influence of weather on human health has a very broad range. Under certain weather conditions a higher frequency of morbidity and even mortality is recorded (Hajat and Haines 2002; Enquselassie et al. 1993; Pell and Cobbe 1999; Boulay et al. 1999; Kveton 1991) especially with regard to coronary heart disease and chronic heart failure. Despite efficacious interventions to treat acute myocar- dial infarction (MI) (LIPID Study Group 1998; Freemantle et al. 1999; ACE Inhibitor Myocardial Infarction Collabo- rative Group 1998; Latini et al. 1995; Antithrombotic Trialists’ Collaboration 2002) and despite declining secular trends over the last 25 years, patients who have survived an MI are at increased risk for recurrent ischemic events and heart failure. The occurrence of unstable angina and recurrent MI as well as of heart failure is particularly high during the first half- Int J Biometeorol (2008) 52:535–547 DOI 10.1007/s00484-008-0144-9 The results of this work have been shown in an oral presentation at the 17th International Congress of Biometeorology 2005 in Garmisch- Partenkirchen, Germany. A. Schneider (*) : R. Rückerl : S. Breitner : A. Peters Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Epidemiology, Neuherberg, Germany e-mail: alexandra.schneider@helmholtz-muenchen.de A. Schneider : A. Schuh Institute of Health and Rehabilitation Sciences, Ludwig-Maximilians-University of Munich, Munich, Germany F.-K. Maetzel Curschmann Clinic, Timmendorfer Strand, Germany