Electrocardiographic diagnosis of myocardial infarction in the presence of bundle branch block or a paced rhythm
- Ary L Goldberger, MD
Ary L Goldberger, MD
- Section Editor — Electrocardiography
- Professor of Medicine
- Harvard Medical School
- Section Editors
- Bernard J Gersh, MB, ChB, DPhil, FRCP, MACC
Bernard J Gersh, MB, ChB, DPhil, FRCP, MACC
- Editor-in-Chief — Cardiovascular Medicine
- Section Editor — Coronary Heart Disease; Myopericardial Disease
- Professor of Medicine
- Mayo Medical School
- Peter J Zimetbaum, MD
Peter J Zimetbaum, MD
- Section Editor — Cardiac Arrhythmias
- Associate Professor of Medicine
- Harvard Medical School
The diagnosis of myocardial infarction (MI) is typically suspected from the history of chest pain and may be confirmed by the electrocardiogram (ECG) and elevations in serum troponins and CK-MB. (See "Criteria for the diagnosis of acute myocardial infarction" and "Electrocardiogram in the diagnosis of myocardial ischemia and infarction".)
The ECG diagnosis of an acute MI in patients with right or left bundle branch block (RBBB or LBBB) or a paced rhythm will be reviewed here. Other issues related to RBBB and LBBB are discussed separately. (See "Right bundle branch block" and "Left bundle branch block".)
The electrocardiogram (ECG) diagnosis of myocardial infarction (MI) is more difficult when the baseline ECG shows a bundle branch block pattern that may precede or be a complication of the infarct or the patient has a paced rhythm [1-5]. The frequency of bundle branch block was best assessed in a review of almost 300,000 infarctions from the National Registry of Myocardial Infarction 2 investigators . Right bundle branch block was present in approximately 6 percent and left bundle branch block in 7 percent of infarctions. Patients with bundle branch block were significantly less likely than those without bundle branch block to receive appropriate therapy with aspirin or beta blockers, had more comorbid disease, and had a significant increase in in-hospital mortality.
RIGHT BUNDLE BRANCH BLOCK WITH MI
The effect of right bundle branch block (RBBB) must be considered in both Q wave (ST elevation) and non-Q wave (non-ST elevation) infarctions.
Q wave MI — Right bundle branch block does not usually interfere with the diagnosis of a Q wave myocardial infarction (MI). MI most often involves the left ventricle and therefore affects the initial phase of ventricular depolarization, sometimes producing abnormal Q waves. In contrast, right bundle branch block (RBBB) primarily affects the terminal phase of ventricular depolarization, producing a wide R' wave in the right chest leads and a wide S wave in the left chest leads (waveform 1A-B). These changes are due to delayed depolarization of the right ventricle, while depolarization of the left ventricle is not affected. (See "Right bundle branch block".)
- Goldberger AL. Myocardial infarction: Electrocardiographic differential diagnosis, 7th, Elsevier/Mosby, St Louis 2006.
- Wackers FJ. The diagnosis of myocardial infarction in the presence of left bundle branch block. Cardiol Clin 1987; 5:393.
- Sgarbossa EB, Pinski SL, Barbagelata A, et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) Investigators. N Engl J Med 1996; 334:481.
- Wellens HJ. Acute myocardial infarction and left bundle-branch block--can we lift the veil? N Engl J Med 1996; 334:528.
- Sgarbossa EB, Pinski SL, Gates KB, Wagner GS. Early electrocardiographic diagnosis of acute myocardial infarction in the presence of ventricular paced rhythm. GUSTO-I investigators. Am J Cardiol 1996; 77:423.
- Go AS, Barron HV, Rundle AC, et al. Bundle-branch block and in-hospital mortality in acute myocardial infarction. National Registry of Myocardial Infarction 2 Investigators. Ann Intern Med 1998; 129:690.
- Gussak I, Wright RS, Bjerregaard P, et al. False-negative and false-positive ECG diagnoses of Q wave myocardial infarction in the presence of right bundle-branch block. Cardiology 2000; 94:165.
- Gussak I, Zhou SH, Rautaharju P, et al. Right bundle branch block as a cause of false-negative ECG classification of inferior myocardial infarction. J Electrocardiol 1999; 32:279.
- Ortega-Carnicer J, Gómez-Grande ML, Ambrós A. Right bundle branch block-induced Q waves simulating anterior myocardial infarction extension. J Electrocardiol 2000; 33:387.
- Shettigar UR, Pannuri A, Barbier GH, Appunn DO. Significance of anterior Q waves in left anterior fascicular block--a clinical and noninvasive assessment. Clin Cardiol 2002; 25:19.
- Kontos MC, McQueen RH, Jesse RL, et al. Can myocardial infarction be rapidly identified in emergency department patients who have left bundle-branch block? Ann Emerg Med 2001; 37:431.
- Shlipak MG, Lyons WL, Go AS, et al. Should the electrocardiogram be used to guide therapy for patients with left bundle-branch block and suspected myocardial infarction? JAMA 1999; 281:714.
- Sgarbossa EB. Value of the ECG in suspected acute myocardial infarction with left bundle branch block. J Electrocardiol 2000; 33 Suppl:87.
- Shlipak MG, Go AS, Frederick PD, et al. Treatment and outcomes of left bundle-branch block patients with myocardial infarction who present without chest pain. National Registry of Myocardial Infarction 2 Investigators. J Am Coll Cardiol 2000; 36:706.
- Smith SW, Dodd KW, Henry TD, et al. Diagnosis of ST-elevation myocardial infarction in the presence of left bundle branch block with the ST-elevation to S-wave ratio in a modified Sgarbossa rule. Ann Emerg Med 2012; 60:766.
- Al-Faleh H, Fu Y, Wagner G, et al. Unraveling the spectrum of left bundle branch block in acute myocardial infarction: insights from the Assessment of the Safety and Efficacy of a New Thrombolytic (ASSENT 2 and 3) trials. Am Heart J 2006; 151:10.
- Tabas JA, Rodriguez RM, Seligman HK, Goldschlager NF. Electrocardiographic criteria for detecting acute myocardial infarction in patients with left bundle branch block: a meta-analysis. Ann Emerg Med 2008; 52:329.
- Laham CL, Hammill SC, Gibbons RJ. New criteria for the diagnosis of healed inferior wall myocardial infarction in patients with left bundle branch block. Am J Cardiol 1997; 79:19.
- Gunnarsson G, Eriksson P, Dellborg M. ECG criteria in diagnosis of acute myocardial infarction in the presence of left bundle branch block. Int J Cardiol 2001; 78:167.
- GENERAL PRINCIPLES
- RIGHT BUNDLE BRANCH BLOCK WITH MI
- Q wave MI
- Non-Q wave MI
- LEFT BUNDLE BRANCH BLOCK WITH MI
- Acute MI
- - Attempts to improve ECG diagnosis
- - Sgarbossa criteria
- - Ventricular pacing
- Prior infarction
- - Left ventricular free wall
- - Anteroseptal
- - Free wall and septal
- - Inferior wall