Prevalence of Silent and Atypical Myocardial Infarction by Gender
Women experience unrecognized myocardial infarction at substantially higher rates than men, with approximately 30-54% of MIs in women being unrecognized compared to 16-33% in men, representing nearly double the rate of silent presentations. 1, 2
Overall Prevalence of Silent MI
The landmark Framingham Study established that up to half of all myocardial infarctions may be clinically silent and unrecognized by patients, with more than 25% discovered only through routine electrocardiographic examinations. 3, 4, 5 Of these unrecognized infarctions, almost half were completely silent, while the remainder caused atypical symptoms that were not recognized as cardiac in origin. 5, 6
Contemporary population-based data confirms this remains a significant problem, with one-third of 434,877 patients with confirmed MI in the National Registry of Myocardial Infarction presenting without chest discomfort. 3
Gender-Specific Prevalence Data
Women's Higher Burden
Women consistently demonstrate higher rates of unrecognized MI across multiple large studies:
- In the Framingham Study, 35% of MIs in women were unrecognized compared to 28% in men. 6
- In the Rotterdam Study of adults aged 55+, 54% of incident MIs in women were unrecognized versus only 33% in men - women had nearly twice the proportion of silent events despite similar overall incidence rates (3.6 vs 4.2 per 1000 person-years). 2
- In the Lifelines Cohort Study of 97,203 individuals, 30% of MIs in women were unrecognized compared to 16% in men (P<0.001), representing an 88% higher rate of silent presentations in women. 1
The proportion of unrecognized infarctions in women remains consistently higher across all age groups, independent of age adjustment. 2
Atypical Symptom Presentations
Current Evidence on Gender Differences
Recent high-quality data contradicts older assumptions about women presenting without chest pain. In the Global Registry of Acute Coronary Events and the Edinburgh study (2013-2017), men and women presented equally with chest pain (91-92% in both sexes). 3, 7 However, women are significantly more likely to have additional atypical symptoms alongside chest pain:
- Jaw pain: 10% in women vs 4% in men 3, 7
- Nausea/vomiting: 32% in women vs 23% in men 3
- Back pain, dyspnea, and diaphoresis occur more frequently in women 3, 7
In the VIRGO study of patients ≤55 years, 61.9% of women versus 54.8% of men reported pain in the jaw, neck, arms, or between shoulder blades. 7
High-Risk Populations for Silent MI
Maintain heightened clinical suspicion in these groups where silent MI is most prevalent:
- Women of all ages (consistently 1.5-2× higher rates than men) 1, 6, 2
- Older adults (both sexes, but especially women >75 years) 3
- Patients with diabetes mellitus (autonomic neuropathy blunts pain perception) 3, 8
- Patients with prior heart failure 3
- Patients with permanent pacemakers (ECG changes may be masked) 3
Clinical Consequences of Missed Diagnosis
Silent MI carries mortality rates 2.4 times higher than recognized MI, with in-hospital mortality of 23.3% versus 9.3% for symptomatic presentations. 3, 4 This excess mortality stems from:
- Delayed presentation (mean 7.9 hours vs 5.3 hours for symptomatic MI) 3, 4
- Underdiagnosis on admission (22.2% vs 50.3% correctly diagnosed) 3, 4
- Less aggressive treatment (lower rates of fibrinolysis, primary PCI, aspirin, beta-blockers, and heparin) 3, 4
Women presenting later after symptom onset (median 300 vs 238 minutes in men) further compounds these disparities. 3
Critical Diagnostic Approach
Obtain a 12-lead ECG within 10 minutes for any patient with cardiac risk factors presenting with:
- Unexplained dyspnea (carries >2× mortality risk even without chest pain) 3, 4
- Epigastric discomfort, nausea, or "indigestion" 7
- Isolated jaw, neck, or back pain 3, 7
- Generalized weakness or fatigue (especially elderly women) 4, 7
- Diaphoresis without clear cause 4, 7
Use sex-specific high-sensitivity troponin thresholds (>16 ng/L for women, >34 ng/L for men), which reclassified 30% of women as having STEMI who would have been missed using conventional thresholds. 3 Serial troponin measurements remain essential even without typical symptoms. 4, 8
Common Pitfalls to Avoid
Never dismiss atypical symptoms in women as non-cardiac without ECG and troponin evaluation. Traditional risk scores and physician gestalt consistently underestimate cardiac risk in women and misclassify them as having nonischemic pain. 7
Do not assume relief with nitroglycerin confirms or excludes cardiac ischemia - this is not a valid diagnostic criterion. 7
Avoid attributing symptoms to gastrointestinal, musculoskeletal, or anxiety disorders in high-risk patients (women >50, diabetics, elderly) without first excluding ACS. 7
Women are less likely to undergo coronary angiography (73.8% vs 84.3% in men) and receive guideline-directed therapies, contributing directly to worse outcomes. 3