Prolonged pain after myocardial infarctions associated with increase in risk of all-cause mortality

In a recent study published in the Journal of the American Heart Association, researchers from Sweden examined the association between different severity levels of pain a year after myocardial infarction and the risk of all-cause mortality.

Background

Although myocardial infarctions have been a leading cause of death globally, fatality rates associated with it are decreasing. However, individuals who survive a myocardial infarction are at an increased risk of recurrent myocardial infarctions, as well as other cardiovascular diseases in the long term.

Moreover, while musculoskeletal problems such as pain are known to be associated with long-term disability, the duration and severity of pain are also linked to an increase in cardiovascular disease risk and all-cause mortality.

Furthermore, socioeconomic factors, obesity, and lifestyles involving smoking, poor diet, and low physical activity levels are common risk factors for cardiovascular disease and chronic pain.

Additional factors such as disturbed sleep, and mental health issues including anxiety and depression can exacerbate the risk of cardiovascular disease in individuals with chronic pain.

A shift in the approach to pain, where it is being considered a risk factor for various diseases and mortality rather than just a disease symptom, has brought about considerable progress in the research on pain and rehabilitation for individuals with chronic pain. However, the association between pain and the increased risk of cardiovascular risk surrounding myocardial infarctions needs to be examined further.

About the study

In the present study, the researchers analyzed a prospective cohort of individuals below the age of 75 years with a diagnosed myocardial infarction event recorded between December 2004 and October 2013 in the Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART).

SWEDEHEART is a Swedish quality registry of treatments, outcomes, and patient characteristics of myocardial infarction patients admitted to coronary care centers in the country.

The registry contains information on biochemical test results, comorbidities, anthropometric variables, blood pressure, lifestyle and psychosocial factors, hospital readmissions, medications, outcome measures reported by the patients such as quality of life related to health, physical fitness measures, and attendance in programs associated with cardiac rehabilitation.

A sub-registry consisting of information on visits to a cardiac rehabilitation physician or nurse between two months to a year after discharge was also used for the analysis. The analyzed patient data comprised sex, age, body mass index, creatinine levels, hypertension, diabetes, hyperlipidemia, and previous events of myocardial infarction, stroke, percutaneous coronary intervention, or congestive heart failure.

Myocardial infarction events were classified as with or without ST-segment elevation, and information on coronary artery bypass graft surgeries was also included.

A questionnaire during the follow-up conducted one year after hospital discharge assessed five dimensions of health, of which one was pain, with patients rating their pain or discomfort on three levels — none, moderate, or extreme.

Physical activity levels across the week were used to classify patients as active or inactive, and information on smoking behavior was used to determine whether patients were current, previous, or never smokers.

Results

The findings reported that not only was pain highly prevalent one year after myocardial infarction, but its impact on increasing the mortality risk was stronger than that of smoking.

The study found that patients who experienced moderate to extreme levels of pain one year after a myocardial infarction had a higher mortality rate during a follow-up period of 8.5 years than myocardial infarction patients without pain.

Sensitivity analyses to account for reverse causation, and other covariates such as age or sex reported no change in the results. However, the researchers reported that while they were able to account for major lifestyle-related variables, they could not adjust for the use of pain medications or various socioeconomic factors.

They were also unable to analyze cause-specific mortality. Additionally, C-reactive protein, which could be a potential confounder associated with pain sensitivity, was not an included measurement in this analysis. Moreover, the extrapolation of the results to an interethnic population presented a challenge since this study was based solely on the population of Sweden.

Conclusions

Overall, the findings suggested that the mortality rates during an 8.5-year follow-up among myocardial infarction patients experiencing moderate to extreme levels of pain one year after the event were higher than among myocardial infarction patients not experiencing pain.

Furthermore, pain was highly prevalent one year after a myocardial infarction, and its effect in increasing the risk of all-cause mortality was higher than that of smoking.

These findings highlight the need to consider pain as an important factor in determining prognosis in myocardial infarction cases and emphasize the necessity for tailored cardiac rehabilitation and pain management methods.

 

Written by

Dr. Chinta Sidharthan

Chinta Sidharthan is a writer based in Bangalore, India. Her academic background is in evolutionary biology and genetics, and she has extensive experience in scientific research, teaching, science writing, and herpetology. Chinta holds a Ph.D. in evolutionary biology from the Indian Institute of Science and is passionate about science education, writing, animals, wildlife, and conservation. For her doctoral research, she explored the origins and diversification of blindsnakes in India, as a part of which she did extensive fieldwork in the jungles of southern India. She has received the Canadian Governor General’s bronze medal and Bangalore University gold medal for academic excellence and published her research in high-impact journals.