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  • Coronary stenosis as a modifier of the effect of cold spells on the risk of sudden cardiac death: a case-crossover study in Finland

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Epidemiology
Research
Coronary stenosis as a modifier of the effect of cold spells on the risk of sudden cardiac death: a case-crossover study in Finland
  1. Niilo R I Ryti1,
  2. M Juhani Junttila2,
  3. Harri Antikainen3,
  4. Marja-Leena Kortelainen4,
  5. Heikki V Huikuri2,
  6. Jouni J K Jaakkola1
  1. 1 Center for Environmental and Respiratory Health Research (CERH), University of Oulu, Oulu, Finland
  2. 2 Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital, Oulu, Finland
  3. 3 Geography Research Unit, University of Oulu, Oulu, Finland
  4. 4 Department of Forensic Medicine, University of Oulu, Oulu, Finland
  1. Correspondence to Professor Jouni J K Jaakkola; jouni.jaakkola{at}oulu.fi

Abstract

Objective To test the a priori hypothesis that the association between cold spells and ischaemic sudden cardiac death (SCD) is modified by the severity of coronary stenosis.

Methods The home coordinates of 2572 autopsy-verified cases of ischaemic SCD aged ≥35 in the Province of Oulu, Finland, were linked to 51 years of weather data. Cold spell was statistically defined for each home address as unusually cold weather pertinent to the location and time of year. We estimated the occurrence of cold spells during the hazard period (7 days preceding death) and reference periods (the same calendar days over 51 years) in a case-crossover setting applying conditional logistic regression, controlling for temporal trends and stratifying by severity of coronary stenosis.

Results The association between cold spells and ischaemic SCD was stronger among patients with 75%–95% stenosis (OR 2.03; 95% CI 1.31 to 3.17), and weaker to non-existent among patients with <75% stenosis (OR 0.97; 95% CI 0.37 to 2.55) or coronary total occlusion (100% stenosis) (OR 1.01; 95% CI 0.52 to 1.96). Lack of calcium-channel blockers and statin therapy seemed to accentuate the role of stenosis during cold spells.

Conclusions We provide evidence that the association between cold spells and ischaemic SCD is modified by the severity of coronary stenosis. The findings suggest that disturbances in coronary circulation play part in the pathogenesis of SCD during cold weather.

  • cardiac epidemiology
  • sudden cardiac death
  • coronary stenosis
  • cold spell
  • temperature
  • weather

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi.org/10.1136/bmjopen-2017-020865

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    Footnotes

    • JJKJ and HVH have equal senior authorship.

    • Contributors NRIR and JJKJ designed the case-crossover study with clinical input from MJJ and HVH. M-LK performed the medicolegal autopsies during 1998–2011. MJJ and HVH constructed the sudden cardiac death database. HA constructed the weather database and performed the GIS-modeling of daily temperatures at each location. NRIR performed the SAS-programming of weather indices, modeling of health effects, and statistical analyses, and drafted the manuscript with important intellectual content from all authors. All authors approved the version to be published and agreed to be accountable for all aspects of the work.

    • Funding This work was funded by the Research Council for Health, Academy of Finland (grant nos 266314 and 267435), University of Oulu Strategic Funding for CERH, Emil Aaltonen Foundation, Sigrid Juselius Foundation and Foundation for Cardiovascular Disease. The funders of the study had no role in study design, data collection, data analysis, data interpretation, writing of the report or the decision to submit the article for publication. The authors are independent from funders.

    • Competing interests None declared.

    • Patient consent Not required.

    • Ethics approval This study complies with the Declaration of Helsinki and has been approved by the Ethics Committee of the Oulu University Hospital (ID of the approval EETTMK:18/2014). The National Supervisory Authority for Welfare and Health (Valvira) has approved the review of postmortem data by the investigators.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement No additional data available.