High Pain Tolerance May Mask Myocardial Infarction Symptoms
People who experience unrecognized myocardial infarction (MI) have reduced pain sensitivity compared with those who experience recognized MI and this may partially explain the lack of symptoms associated with unrecognized MI, according to a new study.
“The high prevalence and poor prognosis associated with unrecognized myocardial infarction makes this a hidden public health issue,” said study lead author Andrea Milde Øhrn, MD, of the department of community medicine at the University of Tromsø in Norway.
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The researchers conducted a population-based cross-sectional study with 4849 participants who underwent the cold pressor test (a common experimental pain assay) and ECG. They found unrecognized MI present in 387 (8%) and recognized MI in 227 (4.7%) participants. Those with unrecognized MI endured the cold pressor test significantly longer than participants with recognized MI (hazard ratio for aborting the cold pressor test, 0.64), adjusted for age and sex. The association was attenuated and borderline significant after multivariable adjustment. The association between unrecognized MI and lower pain sensitivity was stronger in women than in men, and statistically significant in women only, but interaction testing was not statistically significant.
“Absence of chest pain should not lower alertness of doctors towards ischemic heart disease,” Dr Øhrn said. “Questions on pain sensitivity or factors that affect this might be important in the assessment of patients at risk for cardiovascular disease.”
Dr Øhrn said they have two ongoing studies about unrecognized MI: One on the differences in vascular pathology between unrecognized and recognized infarction and the other on sex differences in prognosis associated with unrecognized MI.
—Mike Bederka
Reference:
Øhrn AM, Nielsen CS, Schirmer H, et al. Pain tolerance in persons with recognized and unrecognized myocardial infarction: a population-cased, cross-sectional study [published online Dec 21, 2016]. J Am Heart Assoc. 10.1161/JAHA.116.003846.