Myocardial infarction outcomes: redressing sex

In spite of major medical advances in diagnosis and treatment, cardiovascular disease (CVD) is still the leading cause of mortality in the Western world accounting for 51 percent of female and 42 percent of male deaths. Around half of these deaths are due to coronary heart disease, and it has been recognized for more than two decades that the outcome for women with acute coronary disease (ACD) is worse than it is for men. Quite apart from the fact that surveys show older women are less aware of their risk of myocardial infarction (MI) than men, women presenting with MI are less likely to be appropriately diagnosed.
Various explanations have been given for this disparity. Clinical symptoms of ACD in women may not be the ‘typical’ sudden severe chest pain; physicians have even attributed female symptoms of more diffuse pain, dyspnea and fatigue to falling levels of estrogen and progesterone. And although sex differences in electrocardiography (ECG) were first reported around 90 years ago, with recent studies emphasizing that normal values of the adult ECG should be both age- and sex-specific, the use of sex-specific diagnostic criteria is still not routine in many hospitals. In addition clinical research into ACD was biased towards men in the past, resulting in predictive values for analytes that are not necessarily appropriate for women; results of diagnostic tests should of course take sex-related differences into consideration. Given that the diagnosis of MI relies on a combination of clinical examination, suggestive ECG abnormalities and a rise and fall of key cardiac biomarkers, it is not surprising that myocardial infarction in women is still under-diagnosed.
However, the results of a recently published study in the BMJ should be a step towards more effective diagnosis. The troponin I level of 1126 consecutive patients presenting at a regional cardiac centre with suspected MI, 46% of whom were women, was measured using a high sensitivity assay and sex-specific diagnostic thresholds (men 34 ng/L, women 16 ng/L) in place of the current recommended threshold of 50 ng/L for both sexes. There was a significant increase in the number of women diagnosed with MI (from 11% to 22%) but the increase in men (19% to 21%) was not significant. Although studies continue to show that even when diagnosed women are less likely to undergo percutaneous coronary interventions or bypass surgery, receive prompt thrombolytic therapy or even be prescribed statins on discharge from hospital, more accurate diagnosis should go a long way towards redressing sex inequalities.