Exercise-Induced QRS Amplitude Changes in Patients with Isolated Myocardial Bridging: A Marker of Myocardial Ischemia

Abstract

Myocardial bridging (MB) of coronary arteries has been considered as an incidental angiographic finding; however, several reports suggest its association with angina pectoris, myocardial ischemia, and even infarction. In this study the authors aimed to assess exercise-induced QRS changes in patients with isolated MB and to compare those with coronary artery disease (CAD) and healthy subjects. The study population consisted of 17 patients with angiographically proven MB (group 1), 16 patients with left anterior descending (LAD) artery stenosis (group 2), and 14 healthy subjects (group 3). Each subject underwent treadmill exercise testing according to Bruce protocol. In each subject amplitude of the Q, R, and S waves in leads aVF and V₅ was measured manually before and immediately after exercise. The Athens QRS score was calculated by subtracting the Q-, R-, and S-wave differences in leads aVF and V₅. Baseline characteristics of each group were similar. There was no difference among the groups with respect to exercise testing parameters (peak heart rate, blood pressure, test duration, etc). In group 1, ST-segment depression ratio was found to be higher than that of group 3 but lower than that of group 2. In group 1, exercise QRS score was found to be lower than that of group 3 while it was higher than that of group 2 (2.9 ±2.3 vs 6.5 ±3.2 p=0.001 and 2.9 ±2.3 vs 2.6 ±2.4 p=0.001, respectively). In patients with MB exercise, QRS score was significantly lower than in those with normal coronary flow while it was higher in those with CAD. This may result from exercise-induced ischemia at the area perfused by the bridged artery.

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References

Berry JF , von Mering GO , Schmalfuss C , et al : Systolic compression of the left anterior descending coronary artery: A case series, review of literature, and therapeutic options including stenting. Cathet Cardiovasc Interv 56:58-63, 2002.

Noble J , Bourassa MG , Petitclerc R , et al : Myocardial bridging and milking effect of left anterior descending coronary artery: Normal or obstruction? Am J Cardiol 37:993-999, 1976.

Ge J , Erbel R , Rupprecht HJ , et al : Comparison of intravascular ultrasound and angiography in the assessment of myocardial bridging. Circulation 89:1725-1732, 1994.

Schwarz ER , Klues HG , vom Dahl J , et al : Functional characteristics of myocardial bridging. A combined angiographic and intracoronary Doppler flow study. Eur Heart J 18:434-442, 1997.

Tauth J , Sullebarger JT: Myocardial infarction associated with myocardial bridging: Case history and review of literature. Cathet Cardiovasc Diagn 40:364-367, 1997.

Den Dulk K , Brugada P , Braat S , et al : Myocardial bridging as the cause of paroxysmal atrioventricular block. J Am Coll Cardiol 1:1965-1970, 1983.

Desseigne P , Tabib A , Loire R: Myocardial bridging on the left anterior descending coronary artery and sudden death. Apropos of 19 cases with autopsy. Arch mal Coeur Vaiss 84:511-516, 1991.

Borer JS , Brensike JF , Redwood DR , et al : Limitations of the electrocardiographic response to exercise in predicting coronary artery disease. N Engl J Med 293:367, 1975.

Detrano R , Gianrossi R , Mulvihill D , et al : Exercise-induced ST segment depression in diagnosis of coronary artery disease. A meta-analysis. Circulation 80:87-98, 1989.

10.

Sato I , Keta K , Aihara N , et al : Improved accuracy of the exercise electrocardiogram in detection of coronary artery and three-vessel coronary disease. Chest 94:737-744, 1988.

11.

Michaelides AP , Triposkiadis FK , Boudoulas H , et al : New coronary artery disease index based on exercise-induced QRS changes. Am Heart J 120:292-302, 1990.

12.

Famularo MA , Paliwal Y , Redd R , et al : Identification of septal ischemia during exercise by Q-wave analysis: Correlation with coronary angiography. Am J Cardiol 51:440-443, 1983.

13.

Furuse T , Mashiba H , Jordan JW , et al : Usefulness of Q-wave response to exercise as a predictor of coronary artery disease. Am J Cardiol 59:57-60, 1987.

14.

Wolthuis RA , Froelicher VF , Hopkirk A , et al : Normal electrocardiographic wave-form characteristics during treadmill exercise testing. Circulation 60:1028-1035, 1979.

15.

Charlap S , Shani J , Schulhoff N , et al : R- and S-wave amplitude changes with acute anterior transmural ischemia. Correlations with left ventricular filling pressures. Chest 97:566-571, 1990.

16.

Van Campen CMC , Visser FC , Visser CA: The QRS score: A promising new exercise score for detecting coronary artery disease based on exercise-induced changes of Q, R, and S waves: A relationship with myocardial ischemia. Eur Heart J 17:699-708, 1996.

17.

Toth A , Marton Z , Czopf L , et al : QRS score: A composite index of exercise-induced changes in the Q, R, and S waves during exercise stress testing in patients with ischemic heart disease. Ann Noninvasive Electrocardiol 6:310-318, 2001.

18.

Chambers JD Jr , Johns JP , Berndt TB , et al : Myocardial stunning resulting from systolic coronary artery compression by myocardial bridging. Am Heart J 128:1036-1038, 1994.

19.

Yetman AT , McCrindle BW , MacDonald C , et al : Myocardial bridging in children with hypertrophic cardiomyopathy—a risk factor for sudden death. N Engl J Med 339:1201-1209, 1998.

20.

Iversen S , Hake U , Mayer E , et al : Surgical treatment of myocardial bridging causing coronary artery obstruction. Scand J Thorac Cardiovasc Surg 26:107-111, 1992.

21.

Feld H , Guadanino V , Hollander G , et al : Exercise-induced ventricular tachycardia in association with a myocardial bridge. Chest 99:5:1295-1296, 1991.

22.

Morales AR , Romanelli R , Boucek RJ: The mural left anterior descending coronary artery, strenuous exercise and sudden death. Circulation 62:230-237, 1980.

23.

Ramos SG , Montenegro AP , Felix PR , et al : Occlusive thrombosis in myocardial bridging. Am Heart J 125:1771-1773, 1993.

24.

Ciampricotti R , el Gamal M : Vasospastic coronary occlusion associated with a myocardial bridge. Cathet Cardiovasc Diagn 14:118-120, 1988.

25.

Kuhn FE , Reagan K , Mohler ER III , et al : Evidence for endothelial dysfunction and enhanced vasoconstriction in myocardial bridges. Am Heart J 122:1764-1766, 1991.

26.

Klues HG , Schwarz ER , vom Dahl J , et al : Disturbed intracoronary hemodynamics in myocardial bridging: Early normalization by intracoronary stent placement. Circulation 96:2905-2913, 1997.

27.

de Winter RJ , Kok WE , Piek JJ : Coronary atherosclerosis within a myocardial bridge, not a benign condition. Heart 80:91-93, 1998.

28.

Ge J , Jeramies A , Rupp A , et al : New signs characteristic of myocardial bridging demonstrated by intracoronary ultrasound and Doppler. Eur Heart J 20:1707-1716, 1999.

29.

Ribisl PM , Liu J , Mousa I , et al : Comparison of computer ST criteria for diagnosis of severe coronary artery disease. Am J Cardiol 71:546-551, 1993.

30.

Koide Y , Yotsukura M , Yoshino H , et al : A new coronary artery disease index of treadmill exercise electrocardiograms based on the step-up diagnostic method. Am J Cardiol 87:142-147, 2001.

31.

Cin VG , Celik M , Ulucan S : Relationship between QRS score and the extent of coronary artery disease. Jpn Heart J 38:787-792, 1997.

32.

Michaelides A , Ryan JM , Bacon JP , et al : Exercise-induced QRS changes (Athens QRS score) in patients with coronary artery disease: A marker of myocardial ischemia. J Cardiol 26:263-272, 1995.