Seasonal variation in Takotsubo syndrome compared with myocardial infarction: ANZACS-QI 16.

BACKGROUND: The incidence of myocardial infarction (MI) is characterised by seasonal variation, with a winter peak and summer trough. Takotsubo syndrome (TS) mimics MI, but is thought to have a distinct aetiology and may exhibit a reversed pattern of seasonal variation. This study investigated the seasonal variation in the incidence of TS in comparison to MI.

METHODS: Two hundred and sixty consecutive patients with TS (95% women, median age 66 years) admitted between March 2004 and December 2016 in the Auckland region of New Zealand were identified. The study population was grouped into three-month intervals (seasons) according to the date of admission to analyse for potential seasonal variations in the incidence. The TS cohort was compared with 36,376 patients who presented with acute MI in the Auckland region (40% women, median age 71 years) between March 2004 and December 2016.

RESULTS: The onset of TS differed as a function of season (p=0.02), with the events most frequent in summer (n=77, 30%) and least so in winter (n=46, 18%). In contrast, incidence of MI also varied by season (p=0.0003), with highest events in winter and lowest in summer.

CONCLUSION: The pattern of seasonal variation in TS is reversed compared with MI, with peaks during summer.