Incidence of Coronary Thrombosis in Relation to Climate

Seasonal Pattern of Acute Myocardial Infarction in the National Registry of Myocardial Infarction

“…None of these characteristics would be expected to influence the seasonal pattern of AMI cases reported to NRMI-1. Unlike other studies that have shown a higher prevalence of deaths attributed to AMI in the winter than in the summer, this investigation found more cases of AMI in both winter and spring than in summer (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)23). It is possible that the differences may be due to the fact that other studies have defined the seasons as arbitrary blocks of 3 months rather than by the official calendar definition.…”

“…Variations in platelet aggregability and sympathetic activity have been proposed to explain the observation, but the actual mechanism is not completely understood (1)(2)(3)(4)(5)(6). Although it is known that short-term climatic changes (e.g., a heat wave) can influence cardiovascular morbidity and mortality transiently, investigators throughout the world (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) have reported that there is a seasonal pattern of deaths due to AMI with more fatal events in winter than in summer. However, it is unclear whether this observation is due to variation in the prevalence of AMI or to other factors that may alter the likelihood of a fatal outcome.…”

Seasonal variation in incidence of acute myocardial infarction in a sub-Arctic population: the Tromsø Study 1974-2004

“…Two studies of coronary thrombosis from the 1930s using the same data material found no seasonal pattern when the year was divided into autumn-winter and spring-summer, 21 whereas the division winterspring and summer-autumn gave significant seasonal variation. 22 Several studies suggest that the mortality increase in winter compared with nonwinter seasons is larger in geographic areas with mild winters compared with areas with colder winters. 5,[23][24][25] This observation has been termed the 'paradox of excess winter mortality'.…”

Demographic, seasonal, and spatial differences in acute myocardial infarction admissions to hospital in Melbourne Australia

“…Several studies have described a seasonal fluctuation in cardiac mortality and morbidity in the northern hemisphere with increased rates during the colder months [ 1 - 5 ]. Winter increases in Acute Myocardial Infarction (AMI) mortality in America were first described in 1937 [ 6 , 7 ]. Subsequent studies from Europe, America, and Asia have supported these observations [ 2 , 4 , 8 - 13 ].…”