Inferior Q waves in apparently healthy subjects: Should we take a deep breath? An electrocardiographic, echocardiographic and cardiac magnetic resonance study.

AIM: To evaluate the diagnostic accuracy of electrocardiographic inferior Q waves persistence during inspiration and echocardiographic segmental wall motion abnormalities for the detection of previously unsuspected silent myocardial infarction, by using cardiac magnetic resonance as the gold standard. METHODS: We prospectively enrolled 50 apparently healthy subjects with inferior Q waves on routine electrocardiogram and high atherosclerotic risk profile. Patients underwent electrocardiogram during deep inspiration, standard transthoracic echocardiography, and cardiac magnetic resonance. RESULTS: Inferior Q waves during deep inspiration persisted in 10 subjects (20%) and cardiac magnetic resonance was positive in 10 (20%). Between the 10 positive cardiac magnetic resonance subjects 8 showed persistence of inferior Q waves, giving a sensitivity of 80% (95%;CI 44.4-97.5%) and a specificity of 95% (95%;CI 83.1-99.4%). Segmental wall motion abnormalities were present overall in 10 subjects (20%), but only in 5 of the 10 positive cardiac magnetic resonance subjects, giving a sensitivity of 87.5% (95% CI 73.2-95.8) and specificity of 50% (95% CI 18.7-81.3). CONCLUSIONS: Electrocardiographic inferior Q waves persistence during deep inspiration is a simple test with a high accuracy for diagnosis of silent myocardial infarction. Standard echocardiography resulted less accurate.