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Scandinavian Cardiovascular Journal
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Christmas holiday triggers of myocardial infarction
Anneli Olsson, Ida Thorén, Moman A. Mohammad, Rebecca Rylance, Pyotr
G. Platonov, David Sparv & David Erlinge
To cite this article: Anneli Olsson, Ida Thorén, Moman A. Mohammad, Rebecca Rylance, Pyotr G.
Platonov, David Sparv & David Erlinge (2021): Christmas holiday triggers of myocardial infarction,
Scandinavian Cardiovascular Journal, DOI: 10.1080/14017431.2021.1983638
To link to this article: https://doi.org/10.1080/14017431.2021.1983638
© 2021 The Author(s). Published by Informa
UK Limited, trading as Taylor & Francis
Group.
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Published online: 29 Sep 2021.
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RESEARCH ARTICLE
Christmas holiday triggers of myocardial infarction
Anneli Olsson , Ida Thoren, Moman A. Mohammad, Rebecca Rylance, Pyotr G. Platonov, David Sparv and
David Erlinge
Department of Cardiology, Clinical Sciences, Skane University Hospital, Lund University, Lund, Sweden
ABSTRACT
Objectives: Christmas holidays have been associated with the highest incidence of myocardial infarction
(MI). We wanted to assess possible triggers of MI during Christmas. Design: A nationwide, retrospective
postal survey with case-control design. All individuals suffering an MI during the Christmas holidays
2018 and 2019 in Sweden were identified through the SWEDEHEART registry and a control group
matched in age and gender with chronic coronary syndrome who did not seek medical attention during
Christmas were asked for participation. Subjects completed a questionnaire asking them to rate 27
potential MI-triggers as having occurred more or less than usual. Results: A total of 189 patients suffering
an MI on Christmas Eve, Christmas Day, or Boxing Day, and 157 patients in the control group responded
to the questionnaire, representing response rates of 66% and 62%, respectively. Patients with MI on
Christmas experienced more stress (37% vs. 21%, p¼ .002), depression (21% vs. 11%, p¼ .024), and
worry (26% vs. 10%, p< .001) compared to the control group. The food and sweets consumption was
increased in both groups, but to a greater extent in the control group (33% vs. 50%, p ¼ .002 and 32%
vs. 43%, p ¼ .031). There were no increases in quarrels, anger, economic worries, or reduced compliance
with medication. Conclusions: Patients suffering MI on Christmas holiday experienced higher levels of
stress and emotional distress compared to patients with chronic coronary syndrome, possibly contributing
to the phenomenon of holiday heart attack. Understanding what factors increase the number of MI
on Christmas may help reduce the excess number of MIs and cardiovascular burden.
ARTICLE HISTORY
Received 22 December 2020
Revised 10 August 2021
Accepted 13 September 2021
KEYWORDS
Myocardial infarction;
Christmas; trigger
Introduction
The annual peak in myocardial infarction (MI) incidence
coinciding with Christmas and New Year holidays has been
well described. The day with the highest incidence has been
reported to be Christmas Eve, with a 37% higher risk of MI
than during a defined control period [1]. Christmas in
Sweden is the main holiday of the year and is celebrated
with close family, mainly on Christmas Eve, 24 December,
but festivities continue through Christmas Day and Boxing
Day. Many family members travel some distance to reunite.
Culinary traditions include an abundant smorgasbord,
which offers a mixture of hot and cold dishes as a buffet.
The holiday is traditionally associated with happiness and
joy, but, from a public health standpoint, often involves
high mortality and morbidity [1]. Hypotheses concerning
the source of this phenomenon include overeating, alcohol,
anxiety, a decline in medication adherence, depression, and
limited access to health care [1–3].
We conducted a nationwide survey to identify the primary
triggers of MI during Christmas, hypothesising that an
increased incidence of MI during the Christmas holidays is
triggered by emotional stressors, physical activity, and
excessive food and alcohol consumption. The hazard trigger
period was defined as 24 h before the onset of MI.
Methods
Study population
We used the nationwide Swedish Web System for
Enhancement and Development of Evidence-based care in
Heart disease Evaluated According to Recommended
Therapies (SWEDEHEART) registry to identify MI cases in
Sweden over the Christmas holidays 2018 and 2019. The
SWEDEHEART registry includes all patients with symptoms
of acute coronary syndrome admitted to a coronary care
unit in Sweden, and collects information on background
characteristics such as age, sex, body mass index, smoking
status, and electrocardiographic findings as well as data of
other examinations, interventions, complications, laboratory
measures, discharge medications, and diagnoses [4].
Combining the SWEDEHEART MI data with data from the
National Population Registry, we included all surviving
patients who were diagnosed with type I MI showing symptom
onset from 24 through 26 December 2018 and 2019.
We selected a control group consisting of an age- and sexCONTACT
David Erlinge David.Erlinge@med.lu.se Department of Cardiology, Lund University, Skane University Hospital, Lund, SE-221 85, Sweden
Supplemental data for this article is available online at here.
ß 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
SCANDINAVIAN CARDIOVASCULAR JOURNAL
https://doi.org/10.1080/14017431.2021.1983638
matched group diagnosed with stable angina and treated
with percutaneous coronary intervention within the five
years prior to inclusion who did not seek medical attention
during Christmas 2018 and 2019.
Study design
In this retrospective case-control study with postal questionnaires,
each subject was asked to answer questions about the
presence of potential triggers compared to what the subject
usually experiences. In addition, a control group was used
to characterize the experience of Christmas in a population
diagnosed with chronic coronary artery disease. The MIChristmas
participants were asked to report the occurrence
of the factors in the 24 h before the onset of symptoms,
while the control group evaluated their occurrence on 24–26
Dec. Possible responses were not at all/not applicable, much
less than usual, a little less than usual, as usual, a little more
than usual, and much more than usual. We distributed a
postal questionnaire (Supplemental material) with a cover
letter and an informed consent form to potential participants.
Questions covered 27 topics in three sections. Activity
contained questions regarding outdoor activities, snow shovelling,
traveling, cooking, cleaning, sexual activity, and sleep
disturbances. A second section consisted of questions related
to emotions: joy, stress, exhilaration, anxiety, depression,
sadness, worry, quarrelling, and others. The third section
included questions regarding the consumption of fatty
foods, sweets, and alcohol. Additional questions dealt with
social gatherings, usual level of physical activity according to
a simplified Fr€andin/Grimby scale [5], presence of symptoms,
and an open question regarding potential stress
inducers. Prior to data collection, the questionnaire was
tested in a smaller group of patients with MI, designed and
coded to obtain validity and reliability [6]. To increase the
response rate, a lottery ticket, stamped returned envelope,
and a reminder letter were used [7]. Demographic data were
obtained from the SWEDEHEART registry. Sampling was
conducted from October 2019 through March 2020.
Participants relating to Christmas 2018 received the questionnaire
in October 2019, and those from Christmas 2019
received the questionnaire in February 2020.
Statistical and content analysis
The collected data were encoded and analysed using SPSS
version 26. Baseline demographics of the groups are presented
as mean and standard deviation for continuous variables
and as counts and percentages for categorical data.
Descriptive polar diagrams are showing patient perception
of an increased presence of the hypothetical trigger from
both groups. Missing data ranged from 2 to 5%
(Supplementary Tables 1–3). Comparison between the proportions
of those who stated increased experience of triggers
in MI-Christmas and control group were made using chisquare
test. If the number of observations was too few,
Fischer’s exact test was used. A p-value of .05 was considered
statistically significant.
The questionnaire provided space to freely formulate
causes of any increased stress. The free text answers were
analysed only by summarizing the content described and
divided into themes, a simpler form of summative content
analysis [8]. This gave five areas illustrated with a pie chart
with absolute frequencies.
Results
Patient characteristics
A total of 542 patients, 287 with MI during Christmas 2018
and 2019 and 255 in the matched control group, were identified
in the SWEDEHEART registry and contacted by mail.
The response rate was 64%. In the MI-Christmas group, 189
(66%) completed the questionnaire and the corresponding
rate was 157 (62%) in the control group. The responders in
the MI-Christmas group were more often male, non-smokers,
with less comorbidity than non-responders. The control
group responders were more often male, non-smokers, and
with less diabetes than non-responders but virtually no difference
in another medical history. Baseline demographic
data of participants and non-responders are presented in
Table 1.
Emotions
The emotions, reported a little more or much more than
usual, that were more prevalent among MI Christmas group
than in the control group were stress (37% vs. 21%,
p ¼ .002), depression (21% vs. 11%, p ¼ .024) and worry
(26% vs. 10%, p < .001) (Figure 1). Other non-significant
frequent emotions were joy (27% vs. 30%, p ¼ .401), exhilaration
(19% vs. 16%, p ¼ .411), happiness (19% vs. 23%,
p ¼ .581), troubles (19% vs. 13%, p ¼ .187), anxiety (18% vs.
11%, p ¼ .058), sadness (13% vs. 15%, p ¼ .514) and loneliness
(11% vs. 12%, p ¼ .687) (Figure 1).
Activities
Reporting a little more or much more than usual of cleaning
activities (9% vs. 21%, p ¼ .001) and outdoor activity (5% vs.
12%, p ¼ .038) were more common in the control group.
Other frequent activities, reported as little more or much
more prevalent than usual were insomnia (21% vs. 16%,
p ¼ .303), cooking (20% vs. 25%, p ¼ .257), physical activity
(11% vs. 8%, p ¼ .346), and long-distance travel (11% vs.
8%, p ¼ .466) (Figure 1). One-fourth (25%) of the respondents
in the MI-Christmas group stated less physical activity
and less outdoor activity than usual with similar findings in
the control group (31% and 27%) (Supplementary Table 1).
Food, alcohol consumption and symptoms
Food (33% vs. 50%, p¼ .002) and sweets (32% vs. 43%,
p¼ .031) consumption a little more or much more than usual,
was more prevalent in the control group compared with the
MI-Christmas group (Figure 1). No differences were seen in
2 A. OLSSON ET AL.
fatty-food (31% vs. 39%, p¼ .129) and alcohol consumption
(16% vs. 23%, p¼ 0,135). 50% in the MI group consumed no
alcohol 24h prior to symptom onset. (Supplementary Table 3).
In the MI-Christmas group, 53% experienced increased chest
pain compared to 8.6% in the control group (p< .001), 44%
fatigue (vs. 16%, p< .001), and 38% dyspnea (vs. 15%,
p< .001) during the 24h preceding MI (Figure 1).
Described causes of stress
Participants had the opportunity to describe any possible
trigger or stress inducer in their own words (Figure 2 and
Supplementary Table 4.). Of the 39 responses from the MIChristmas
group, 12 participants (31%) declared worries
regarding family and relatives. Stress at work was described
by nine responders (23%) and as many stated Christmas
issues and forced socializing as stressful.
Discussion
Patients with MI at Christmas reported stress, depression, and
worry to a greater extent than the control group. Both groups
reported altered diet habits even if consumption of food and
sweets was more common in the control group. No differences
were seen in alcohol and fatty food consumption. The frequency
of quarrels, anger and financial worries did not differ
markedly. About half of the patients with MI at Christmas
experienced warning signs such as chest pain.
Emotions
Emotional stress has been reported in earlier studies to precede
cardiac events [9–11]. This was confirmed in our
study. Although only 7% stated that they were alone over
the Christmas holidays pre-MI (Figure 3), a much higher
Table 1. Baseline demographics of study groups.
MI-Christmas Control group
Characteristics Responders Non-responders Responders Non-responders
Number (%) 189 (65.9) 98 (34.1) 157 (61.6) 98 (38.4)
Mean (SD) age (years) 72.8 (10.3) 72.3 (12.3) 73.3 (9.5) 72.4 (12.6)
Male 130 (68.8) 64 (65.3) 110 (70.0) 67 (68.4)
Mean (SD) BMI 27.3 (4.6) 27.1 (4.9) 27.1 (4.1) 27.6 (4.4)
Current smoker 28 (14.8) 24 (24.5) 11 (7.0) 9 (9.2)
Medical history
Diabetes 46 (24.3) 36 (36.7) 23 (14.6) 22 (22.4)
Hypertension 117 (61.9) 74 (75.5) 131 (83.4) 82 (83.7)
Myocardial infarction 53 (28.0) 41 (41.8) 55 (35.0) 34 (34.7)
PCI 38 (20.1) 29 (29.6) 66 (42.0) 38 (38.8)
CABG 19 (10.1) 8 (8.2) 15 (9.6) 12 (12.2)
Chronic heart failure 11 (5.8) 11 (11.2)
Stroke 9 (4.8) 4 (4.1)
Responders and non-responders. Values are numbers and percentages unless stated otherwise. No baseline data in control
group regarding CHF and stroke are available.
Figure 1. Report of a little more or much more of emotions, activities, food, alcohol, and symptoms than usual in the 24 h pre-MI or 24–26 Dec in the controlgroup.
Values represent the percentage of responders. Ãp < .05, ÃÃp < .01, ÃÃÃp < .001.
Figure 2. Stated reasons for stress from MI-Christmas responders. Categories of
responder descriptions. Values in percent.
SCANDINAVIAN CARDIOVASCULAR JOURNAL 3
proportion reported greater than usual emotional distress.
Of the MI-Christmas group, 52% expressed higher levels
than usual of at least one of the following negative feelings:
anxiety, depression, loneliness, sadness, worry, troubles,
financial worries, and stress. Subjective emotional illness is
multifaceted, and assessment of stress is a challenge, as no
standard methodology exists. The free wording descriptions
of stressors provide insight into both short- and long-term
emotional stress with several responses relating to the loss
of family members. Loss of loved ones has been associated
with a 21-fold increase in MI incidence rate in the initial
24 h, declining in the following days [12]. Work-related
stress has likewise been documented to trigger MI [10,13].
Our group [1] has earlier observed that the risk of MI
during the Christmas holiday period was greater in older
individuals with comorbidities, suggesting that vulnerable
patients may be more susceptible to triggers associated with
the Christmas holidays. In the present study, the mean age
was considerably higher than in many other trials assessing
triggers of MI [14]. A previous study stated that wellbeing
likely plays a protective role in health maintenance [15].
Steptoe et al. [15]shows that the elderly population in
Western countries experiences lower levels of stress, worry,
and anger than do middle-aged individuals. The close relationship
of impaired psychological wellbeing and physical
health is supported by the study, indicating compromised
emotional health preceding MI.
Food and alcohol
More than one-third of MI-Christmas responders described
consuming more food than usual in the 24 h pre-MI.
Associations with MI have been observed in the hours following
ingestion of a heavy meal because of endothelial dysfunction,
excessive gastric distention, and increased blood
pressure [16,17]. Approximately 8% of MIs are considered
to follow meal ingestion [9]. In addition, about one-third of
the MI Christmas group reported increased consumption of
sweets. Elevated insulin and hyperglycaemia can influence
blood vessels through inflammation, endothelial dysfunction,
and increased platelet adhesiveness; hence, a short-term trigger
effect similar to overeating is likely [18]. Increased
consumption of food and sweets was more prevalent in the
control group than in the MI group contradicting the
expected relationship between increased food intake and MI
during Christmas. The fact that the control group reported
variables over 3 days, compared to 24 h for the MI group
could be a reason, in addition, pre-symptoms and reduced
psychological well-being in the MI group reduced appetite
could influence. Moderate alcohol consumption has been
associated with an increased risk of cardiovascular disease in
the first 24 h after consumption [19]. Overall alcohol consumption
was low in this study, 50% consumed no alcohol
(Supplementary Table 3), and it does not seem to be the
main factor in the increased number of MIs at Christmas.
Activity
Except for cooking and cleaning, reduced physical and outdoor
activity was common in our study, with one in four responders
in the Christmas-MI group reporting less physical activity
than usual. This was also true of almost one-third of the group
of patients in the control group. Although our results did not
indicate it as a major trigger of MI during the Christmas holidays,
physical exertion as a trigger of MI has been well
described [16,18], and one patient in the MI-Christmas group
was skiing when MI symptoms developed. We also asked
about poor compliance with prescribed medication, which has
been speculated to be associated with increased cardiac events
during holidays. Only three responders (2%) admitted to lower
than usual compliance in the MI-Christmas group. Drug
adherence can however be quite challenging to measure and
self-reported answers have limitations [20]. About half of the
MI-Christmas patients experienced chest pain, fatigue, or dyspnea
in the 24h pre-MI which may have been a warning sign.
Strengths and limitations
The main limitation of this study is recall bias [21], compounded
by the increased likelihood of reporting retrospective
psychological illness when trying to find a reason for a
physical disorder. The experience could be remembered as
more intense or more proximate to the MI than it was. An
earlier study has although shown that, on average, positive
emotions were retrospectively overestimated, whereas negative
emotions were recalled more accurately [21]. However,
we used a common design in patient-reported outcomes,
and it is difficult to investigate this topic prospectively. In
addition, we used 24 h as a hazard period to identify triggers,
while most previous studies have used one to two
hours. Our main objective was to obtain the patient view of
the time pre-MI to understand the mechanisms behind the
higher heart attack rate during Christmas.
As no validated questionnaire was available, we constructed
our own by using standard instruments in combination
with our survey questionnaire [22]. The responders
were instructed to value any possible action, feeling, or food
consumption relative to “as usual.” The interpretation of
this was left to the responders and objective scales were not
used for most topics. This design has limitations even as it
Figure 3. Socializing in the 24 h pre-MI in the MI-Christmas group. Values represent
percentages of responders.
4 A. OLSSON ET AL.
reduces differences in patient perception. Despite the lag
time from the MI event to answering the questionnaire,
most of the responders remember the circumstances. The
first-year results and the response rates were almost identical
to those of the second year, and the same conclusions
could be drawn. A final limitation could be that this study
assessed only triggers of Christmas MI in surviving patients.
This study benefits from many strengths including being a
nationwide survey study with high response rates assessing a
large number of potential MI triggers.
Conclusions
The main findings in this nationwide survey are increased
stress and impaired psychological wellbeing as potential triggers
to Christmas-MI. Awareness of impaired psychological
wellbeing preceding the myocardial infarction is important to
deal with in the secondary prevention care. Other potential
reasons for Christmas-MI, like food, sweets, quarrel, or economic
worries are not shown to be major triggers in
this study.
Ethical approval
This study was approved by Swedish Ethical Review Authority
(2019/01586).
Author contributors
All authors were involved in the study design, data analysis, and revision
of the manuscript and read and approved the final manuscript.
DE is the guarantor. The corresponding author attests that all listed
authors meet authorship criteria and that no others meeting the criteria
have been omitted.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Funding
This work was supported by The Swedish Heart Lung Foundation,
Swedish Scientific Research Council, Knut and Alice Wallenberg
Foundation, ALF, the Bundy Academy and Skane University Hospital
funds. The sponsors had no involvement in the study design, collection,
analysis or interpretation of data or writing of the manuscript or
in the decision to submit the manuscript for publication.
ORCID
Anneli Olsson http://orcid.org/0000-0001-9589-7225
Data availability statement
The data that support the findings of this study are available from the
corresponding author, [DE], upon reasonable request.
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