Short answer: Yes! Q-waves may regress following transmural myocardial infarction (ATMI) and in fact this phenomenon may not be as unusual as once thought, occurring in 7-15% of patients (1,2).
A prospective study involving patients with ATMI evaluated by coronary angiography and followed for an average of 65 months found an 11% rate of loss of Q-waves over an average of 14 months after ATMI. Factors associated with loss of Q-waves included lower peak creatine kinase values, lower left ventricular end-diastolic pressures, higher ejection fractions, fewer ventricular aneurysms and lower rate of congestive heart failure, all leading to the authors’ conclusion that Q-wave loss may be related to a smaller infarct size (1).
Similar findings were reported from patients enrolled in the Aspirin Myocardial Infarction Study with a loss of a previously documented diagnostic Q-wave confirmed in 14.2% of participants over an average of 38 months. Mortality among patients who lost Q-waves was not significantly different than among those with persistent Q-waves in a single infarct location (2).
These observations suggest that Q-waves in the setting of ATMI may not necessarily be pathognomonic of myocardial necrosis and, at least in some instances, may be due to tissue ischemia, edema and inflammation causing reversible myocardial and electrical stunning (3). Of interest, reversible Q-waves have also been reported in acute myocarditis (4).
Bonus Pearl: Did you know that the EKG waves P and Q were likely named by Einthoven, the inventor of EKG, after the designation of the same letters by Descartes, the father of analytical geometry, in describing refraction points? (5).
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References
1. Coll S, Betriu A, De Flores T, et al. Significance of Q-wave regression after transmural acute myocardial infarction. Am J Cardiol 1988;61:739-42.
2. Wasserman AG, Bren GB, Ross AM, et al. Prognostic implications of diagnostic Q waves after myocardial infarction. Circulation 1982;65:1451-55.
3. Barold SS, Falkoff MD, Ong LS, et al. Significance of transient electrocardiographic Q waves in coronary artery disease. Cardiol Clin 1987;5:367-80.
4. Dalzell JR, Jackson CE, Gardner RS. Masquerade: Fulminant viral myocarditis mimicking a Q-wave anterolateral myocardial infarction. Am J Med 2009. Doi:10.1016/j.amjmed.2009.01.015.
5. Hurst, JW. Naming of the waves in the ECG, with a brief account of their genesis. Circulation 1998;98:1937-42.
