Seasonal variations in cardiovascular disease

Abstract

Cardiovascular disease (CVD) follows a seasonal pattern in many populations. Broadly defined winter peaks and clusters of all subtypes of CVD after 'cold snaps' are consistently described, with corollary peaks linked to heat waves. Individuals living in milder climates might be more vulnerable to seasonality. Although seasonal variation in CVD is largely driven by predictable changes in weather conditions, a complex interaction between ambient environmental conditions and the individual is evident. Behavioural and physiological responses to seasonal change modulate susceptibility to cardiovascular seasonality. The heterogeneity in environmental conditions and population dynamics across the globe means that a definitive study of this complex phenomenon is unlikely. However, given the size of the problem and a range of possible targets to reduce seasonal provocation of CVD in vulnerable individuals, scope exists for both greater recognition of the problem and application of multifaceted interventions to attenuate its effects. In this Review, we identify the physiological and environmental factors that contribute to seasonality in nearly all forms of CVD, highlight findings from large-scale population studies of this phenomenon across the globe, and describe the potential strategies that might attenuate peaks in cardiovascular events during cold and hot periods of the year.

Seasonality in Mortality in a Cardiology Department: A Five-Year Analysis in 500 Patients

“…A vaccination strategy can reduce hospital admissions [21, 23] and may improve heart failure prognosis [21]. Our data are consistent with previous findings [3, 5], and the peak of mortality due to refractory heart failure observed in the cold months can be explained, partially, by the rise in viral infections, including influenza.…”

“…The proposed explanation for this is that socioeconomic conditions, or the ability to protect oneself from the cold (by means of home insulation or appropriate outerwear), and other less clearly defined factors, also play an important role in seasonality [19, 20]. Poor regions are more vulnerable to seasonal threats [3]. …”

“…Thus, it has been reported that heart failure decompensation or acute myocardial infarction is more frequent in autumn and winter, while ventricular arrhythmias may be more common in warmer months [7, 8]. Regarding temperature, it has been hypothesized that total mortality and cardiovascular events follow a U-shaped curve (highest number in extreme climates), although the generalizability of these data may be conditioned by the origin of the studies, which have been carried out, mostly in developed countries with specific climates [3, 5, 9]. …”

“…This seasonal pattern has several potential explanations, such as climate/environmental factors, behavioral changes, or a rise in respiratory infections [3-5]. Circannual rhythms [6] are intrinsic cy­clical variations in the organism functions, including activity, temperature and metabolism control, and hormonal secretion (corticosteroids, catecholamines, thyroid hormones or testosterone) [5, 6], that may also have an impact on disease and mortality incidence throughout the year.…”

“Summer Shift”: A Potential Effect of Sunshine on the Time Onset of ST‐Elevation Acute Myocardial Infarction

“…The fact that onset of STEMI has a circadian rhythm with a peak during diurnal hours has been well described 4, 5, 6, 7, 8, 9, 10, 11, 12. A seasonal pattern13 in the occurrence of STEMI was also found with a salient peak of cases in the winter months and a marked nadir of cases in the summer months 14, 15, 16, 17, 18, 19. Several studies have investigated the reason behind the winter peak and suggested that STEMI is more common in winter and more common on colder days, independent of season 20, 21.…”