Sezonske promjene pojedinih upalnih i hemostatskih pokazatelja i njihova povezanost s klimatskim faktorima u bolesnika s akutnim koronarnim sindromom [Seasonal variations of some inflammatory and haemostatic markers and their association with climatic data in patients with acute coronary syndromes]

Acute myocardial infarction occurs more frequently in certain seasons of the year but the mechanisms that cause seasonal distribution have not been fully understood. Since low-grade systemic inflammation plays an essential role int he atherosclerotic process leading to plaque rupture, seasonal changes of inflammatory markers might be responsible for the increased frequency in cardiovascular events. Aims of the study were to investigate: seasonal variations of acute coronary syndromes (ACS) incidence and their complications (in-hospital mortality rate, heart failure), whether ST-elevation (STEMI) and non-ST-elavation acute coronary syndromes (NST-ACS) exhibit similar changes, seasonal variations of inflammatory and haemostatic marker sin patients (pts) with ACS, their relation to meteorological parameters (air temperature, barometric, pressure, relative humidity, wind speed, rainfall, cloudiness, atmosphere stability) and their association with age. The study included 2223 pts with ACS (51% STEMI) admitted to the University hospital from January 2000 to December 2005 (only pts with < 24 h after the onset of symptoms were included). The following parameters were obtained at the time of admission: fibrinogen, platelet count, plateletcrit, mean platelet volume (MPV), C-reactive protein (CRP), leukocyte count, absolute and relative neutrophil, monocyte and lymphocyte count and neutrophil to lymphocyte ration. A seasonal pattern in the occurrence and complications of AMI was obtained with an increase in cases during the winter months. Both STEMI and NST-ACS exhibit significant seasonal variations. STEMI is characterized by a marked peak of cases in the winter months and a nadir in the summer months, while for NST-ACS the rates were greatest in fall and lowest in summer. After multivariate adjustment, CRP, MVP and relative neutrophil count showed significant seasonal variations, with highest levels recorded in winter and lowest in the summer in STEMI group of pts. Significant difference between seasons was obtained regarding i fibrinogen and MVP in NSTEMI group, with peak values during the fall and trough in summer. The observed seasonal variations of inflammatory and haemostatic markers as well as clustering of their peak values might clarify etiologic mechanisms that cause seasonality of ACS. The greatest frequency of ACS pts was obtained in periods with marked daily pressure changes (i.e. large intradiurnal air pressure fluctuations), when the atmosphere was unstable with humid, cloudy, often windy and very cold weather prevailing. Aforementioned weather conditions were associated with higher values of inflammatory and haemostatic marker sin both STEMI and NST-ACS group, effects being more pronounced at older age. In pts with ACS advanced age was associated with higher levels of fibrinogen, MPV, CRP, absolute and relative neutrophil count and neutrophil to lymphocyte ratio, partly explaining the elevated incidence and more common complications of cardiovascular disease in the elderly