Morphology of QRS complex, especially in leads V1-V6. Differential diagnosis The differential diagnosis of SMVT includes supraventricular tachycardia with aberrant conduction (preexisting or rate-related), supraventricular tachycardia with preexcitation, supraventricular tachycardia in a pacemaker dependent patient, and ECG artifact ( waveform 4). (See 'Differential diagnosis' above.) Cardiac imaging Echocardiography should be performed to evaluate for structural heart disease. If the echocardiographic evaluation is inconclusive, cardiac computed tomography (CT) or magnetic resonance imaging (MRI) should be performed. (See 'Cardiac imaging' above.) Exercise testing All patients should be evaluated for ischemic heart disease. We typically proceed with exercise stress testing (or pharmacologic stress testing if the patient is unable to exercise) with or without cardiac imaging, as clinically appropriate, and coronary angiography when indicated. (See 'Exercise testing' above.) Electrophysiologic studies Invasive electrophysiologic studies can provide a more definitive diagnosis in instances where the diagnosis of ventricular tachycardia (VT) remains uncertain, or in cases where catheter ablation is being considered. However, if the diagnosis of VT is certain, and therapy with an implantable cardiac defibrillator (ICD) placement is planned, electrophysiologic studies are unlikely to affect further management and are not recommended unless catheter ablation is also being planned. (See 'Electrophysiologic studies' above.) ACKNOWLEDGMENT The UpToDate editorial staff acknowledges Philip J. Podrid, MD, FACC and Leonard Ganz, MD, FHRS, FACC, who contributed to an earlier version of this topic review. Use of UpToDate is subject to the Terms of Use. REFERENCES 1. GBD 2013 Mortality and Causes of Death Collaborators. Global, regional, and national age- sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet 2015; 385:117. https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 12/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate 2. Roth GA, Huffman MD, Moran AE, et al. Global and regional patterns in cardiovascular mortality from 1990 to 2013. Circulation 2015; 132:1667. 3. Myerburg RJ. Sudden cardiac death: exploring the limits of our knowledge. J Cardiovasc Electrophysiol 2001; 12:369. 4. Khurshid S, Choi SH, Weng LC, et al. Frequency of Cardiac Rhythm Abnormalities in a Half Million Adults. Circ Arrhythm Electrophysiol 2018; 11:e006273. 5. Tisdale JE, Chung MK, Campbell KB, et al. Drug-Induced Arrhythmias: A Scientific Statement From the American Heart Association. Circulation 2020; 142:e214. 6. Gupta AK, Thakur RK. Wide QRS complex tachycardias. Med Clin North Am 2001; 85:245. 7. Hayes JJ, Stewart RB, Green HL, Bardy GH. Narrow QRS ventricular tachycardia. Ann Intern Med 1991; 114:460. 8. Militianu A, Salacata A, Meissner MD, et al. Ventriculoatrial conduction capability and prevalence of 1:1 retrograde conduction during inducible sustained monomorphic ventricular tachycardia in 305 implantable cardioverter defibrillator recipients. Pacing Clin Electrophysiol 1997; 20:2378. 9. Miller JM, Das MK. Differential diagnosis of wide complex tachycardia. In: Cardiac electrophy siology: from cell to bedside, 4th, Zipes DP, Jalife J (Eds), Saunders, 2004. p.751. 10. European Heart Rhythm Association, Heart Rhythm Society, Zipes DP, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death). J Am Coll Cardiol 2006; 48:e247. 11. American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Society of Echocardiography, American Heart Association, et al. ACCF/ASE/AHA/ASNC/HFSA/HRS/SCAI/SCCM/SCCT/SCMR 2011 Appropriate Use Criteria for Echocardiography. A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Society of Echocardiography, American Heart Association, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Critical Care Medicine, Society of Cardiovascular Computed Tomography, and Society for Cardiovascular Magnetic Resonance Endorsed by the American College of Chest Physicians. J Am Coll Cardiol 2011; 57:1126. https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 13/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate 12. Priori SG, Blomstr m-Lundqvist C, Mazzanti A, et al. 2015 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: The Task Force for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death of the European Society of Cardiology (ESC). Endorsed by: Association for European Paediatric and Congenital Cardiology (AEPC). Eur Heart J 2015; 36:2793. 13. Ki s P, Bootsma M, Bax J, et al. Arrhythmogenic right ventricular dysplasia/cardiomyopathy: screening, diagnosis, and treatment. Heart Rhythm 2006; 3:225. 14. Marcus F, Towbin JA, Zareba W, et al. Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C): a multidisciplinary study: design and protocol. Circulation 2003; 107:2975. 15. Marcus FI, McKenna WJ, Sherrill D, et al. Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the Task Force Criteria. Eur Heart J 2010; 31:806. 16. Bay s de Luna A, Coumel P, Leclercq JF. Ambulatory sudden cardiac death: mechanisms of production of fatal arrhythmia on the basis of data from 157 cases. Am Heart J 1989; 117:151. 17. Gradman AH, Batsford WP, Rieur EC, et al. Ambulatory electrocardiographic correlates of ventricular inducibility during programmed electrical stimulation. J Am Coll Cardiol 1985; 5:1087. 18. Linzer M, Pritchett EL, Pontinen M, et al. Incremental diagnostic yield of loop electrocardiographic recorders in unexplained syncope. Am J Cardiol 1990; 66:214. 19. Krahn AD, Klein GJ, Yee R, et al. Use of an extended monitoring strategy in patients with problematic syncope. Reveal Investigators. Circulation 1999; 99:406. 20. Kadish AH, Buxton AE, Kennedy HL, et al. ACC/AHA clinical competence statement on electrocardiography and ambulatory electrocardiography. A report of the ACC/AHA/ACP- ASIM Task Force on Clinical Competence (ACC/AHA Committee to Develop a Clinical Competence Statement on Electrocardiography and Ambulatory Electrocardiography). J Am Coll Cardiol 2001; 38:2091. 21. Denniss AR, Richards DA, Cody DV, et al. Prognostic significance of ventricular tachycardia and fibrillation induced at programmed stimulation and delayed potentials detected on the signal-averaged electrocardiograms of survivors of acute myocardial infarction. Circulation 1986; 74:731. 22. Vaitkus PT, Kindwall KE, Marchlinski FE, et al. Differences in electrophysiological substrate in patients with coronary artery disease and cardiac arrest or ventricular tachycardia. Insights https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 14/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate from endocardial mapping and signal-averaged electrocardiography. Circulation 1991; 84:672. 23. Martinez-Rubio A, Shenasa M, Borggrefe M, et al. Electrophysiologic variables characterizing the induction of ventricular tachycardia versus ventricular fibrillation after myocardial infarction: relation between ventricular late potentials and coupling intervals for the induction of sustained ventricular tachyarrhythmias. J Am Coll Cardiol 1993; 21:1624. 24. Ommen SR, Hammill SC, Bailey KR. Failure of signal-averaged electrocardiography with use of time-domain variables to predict inducible ventricular tachycardia in patients with conduction defects. Mayo Clin Proc 1995; 70:132. 25. Steinberg JS, Prystowsky E, Freedman RA, et al. Use of the signal-averaged electrocardiogram for predicting inducible ventricular tachycardia in patients with unexplained syncope: relation to clinical variables in a multivariate analysis. J Am Coll Cardiol 1994; 23:99. 26. Cain, ME, Anderson, et al. Signal-averaged electrocardiography. ACC Expert Consensus Document. J Am Coll Cardiol 1996; 27:238. 27. Hendel RC, Berman DS, Di Carli MF, et al. ACCF/ASNC/ACR/AHA/ASE/SCCT/SCMR/SNM 2009 Appropriate Use Criteria for Cardiac Radionuclide Imaging: A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, the American Society of Nuclear Cardiology, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the Society of Cardiovascular Computed Tomography, the Society for Cardiovascular Magnetic Resonance, and the Society of Nuclear Medicine. J Am Coll Cardiol 2009; 53:2201. 28. Volgman AS, Zheutlin TA, Mattioni TA, et al. Reproducibility of programmed electrical stimulation responses in patients with ventricular tachycardia or fibrillation associated with coronary artery disease. Am J Cardiol 1992; 70:758. 29. Bhandari AK, Hong R, Kulick D, et al. Day to day reproducibility of electrically inducible ventricular arrhythmias in survivors of acute myocardial infarction. J Am Coll Cardiol 1990; 15:1075. Topic 1029 Version 35.0 https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 15/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate GRAPHICS ECG of sustained monomorphic ventricular tachycardia Shown are the six precordial electrocardiogram (ECG) leads (V1-V6). The QRS complex is wide and bizarre and the rhythm is ventricular tachycardia (VT). The sixth (+) and seventh (*) QRS complexes show a change in morphology, resembling a normal QRS complex; these represent fusion beats, with partial (+) or complete (*) normalization of the QRS complex. The seventh QRS complex (*) is preceded by a distinct P wave, which is probably conducted, capturing the ventricle for one beat, but not terminating the VT; this is also known as a Dressler beat. Reproduced with permission by Samuel Levy, MD. Graphic 69201 Version 3.0 https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 16/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate Algorithm for the initial ECG review and differential diagnosis of tachycardia ECG: electrocardiogram; AVNRT: atrioventricular nodal reentrant tachycardia; AVRT: atrioventricular reciprocating (bypass-tract mediated) tachycardia; AT: atrial tachycardia; SANRT: sinoatrial nodal reentrant tachycardia; AF: atrial fibrillation; AV: atrioventricular; VT: ventricular tachycardia; SVT: supraventricular tachycardia; WPW: Wolff-Parkinson-White. A narrow QRS complex is <120 milliseconds in duration, whereas a wide QRS complex is 120 milliseconds duration. Refer to UpToDate topic reviews for additional details on specific ECG findings and management of individu arrhythmias. Monomorphic VT accounts for 80% of wide QRS complex tachycardias; refer to UpToDate topic on diagnosi wide QRS complex tachycardias for additional information on discriminating VT from SVT. Graphic 117571 Version 3.0 https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 17/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate Atrioventricular dissociation Independent activation of the atria and ventricles results in no fixed relationship between the P waves (arrows) and the QRS complexes; the PR intervals are variable in a random fashion. Graphic 52123 Version 2.0 Normal rhythm strip Normal rhythm strip in lead II. The PR interval is 0.15 sec and the QRS duration is 0.08 sec. Both the P and T waves are upright. Courtesy of Morton F Arnsdorf, MD. Graphic 59022 Version 3.0 https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 18/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate 12-lead ECG sustained monomorphic VT The electrocardiogram (ECG) hallmark for the diagnosis of sustained monomorphic ventricular tachycardia (S is a wide complex tachycardia with the obvious presence of atrioventricular (AV) dissociation. AV dissociation suggested by the presence of fusion complexes (which reflect a supraventricular impulse coming from above AV node fusing with an impulse generated in the ventricle) or captured complexes (which reflect an impulse coming from above the AV node that depolarizes the ventricles when they are no longer refractory but befor next ventricle-generated complex). Beats 12, 17, and 22 on this ECG likely represent capture beats. Graphic 111254 Version 1.0 https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 19/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate ECG features of ventricular tachycardia QRS width >120 milliseconds Shift in QRS axis, particularly to a "northwest" axis (between 90 and 180 degrees) AV dissociation (including the presence of fusion complexes and/or capture beats) Negative concordance in leads V1 to V6 RS >100 milliseconds in any of leads V1 to V6 Morphology: VT with RBBB-like morphology in V1: R/S <1 in V6 VT with LBBB-like morphology in V1: Any Q wave in V6 ECG: electrocardiogram; AV: atrioventricular; VT: ventricular tachycardia; RBBB: right bundle branch block; LBBB: left bundle branch block. Graphic 111307 Version 2.0 https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 20/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate Ventricular tachycardia artifact Courtesy of Alfred Buxton, MD. Graphic 140806 Version 1.0 https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 21/22 7/5/23, 10:40 AM Sustained monomorphic ventricular tachycardia: Clinical manifestations, diagnosis, and evaluation - UpToDate Contributor Disclosures Alfred Buxton, MD No relevant financial relationship(s) with ineligible companies to disclose. N A Mark Estes, III, MD Consultant/Advisory Boards: Boston Scientific [Arrhythmias]; Medtronic [Arrhythmias]. All of the relevant financial relationships listed have been mitigated. Nisha Parikh, MD, MPH No relevant financial relationship(s) with ineligible companies to disclose. Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence. Conflict of interest policy https://www.uptodate.com/contents/sustained-monomorphic-ventricular-tachycardia-clinical-manifestations-diagnosis-and-evaluation/print 22/22