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.