toxicity, and polymorphic VT with or without QT prolongation, all of which have specific appropriate therapy. (See "Overview of the acute management of ST-elevation myocardial infarction" and "Overview of the acute management of non-ST-elevation acute coronary syndromes" and "Cardiac arrhythmias due to digoxin toxicity" and "Clinical manifestations and treatment of hypokalemia in adults", section on 'Treatment' and "Acquired long QT syndrome: Clinical manifestations, diagnosis, and management".) Chronic therapy Chronic therapy for patients with WCT will be driven by the underlying etiology of the WCT. Patients with VT should generally undergo implantation of an ICD. Following ICD implantation, those patients with recurrent symptomatic VT, or those who have received multiple ICD therapies, may require adjunctive antiarrhythmic therapy in an effort to suppress recurrent VT. In some cases, radiofrequency catheter ablation may be an option to reduce the frequency of VT. An important exception is idiopathic VT, which is treated with ablation or pharmacologic therapy, not with ICD. (See "Sustained monomorphic ventricular tachycardia in patients with structural heart disease: Treatment and prognosis", section on 'Chronic therapy' and "Secondary prevention of sudden cardiac death in heart failure and cardiomyopathy", section on 'Other treatment options'.) https://www.uptodate.com/contents/wide-qrs-complex-tachycardias-approach-to-management/print 12/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate The approach to patients with WCT due to an SVT will vary significantly depending upon the etiology of the SVT. Patients with AVNRT or AVRT associated with a concealed accessory pathway may require no therapy, may be able to self-terminate arrhythmias using vagal maneuvers, may be candidates for pharmacologic suppressive therapy, or may be effectively cured with catheter ablation. (See "Atrioventricular nodal reentrant tachycardia", section on 'Preventive therapy' and "Treatment of arrhythmias associated with the Wolff- Parkinson-White syndrome", section on 'Treatment to prevent recurrent arrhythmias'.) Patients with AVRT associated with a manifest accessory pathway or pre-excited atrial fibrillation or atrial flutter (ie, patients with arrhythmias related to WPW) should undergo electrophysiology testing and catheter ablation of accessory pathway due to the small risk of sudden cardiac death in patients with symptomatic WPW syndrome. (See "Treatment of arrhythmias associated with the Wolff-Parkinson-White syndrome", section on 'Treatment to prevent recurrent arrhythmias'.) The approach to a patient with atrial fibrillation may include ventricular rate control, restoration of sinus rhythm, or catheter ablation. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".) SOCIETY GUIDELINE LINKS Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Arrhythmias in adults" and "Society guideline links: Ventricular arrhythmias" and "Society guideline links: Cardiac implantable electronic devices" and "Society guideline links: Supraventricular arrhythmias".) SUMMARY AND RECOMMENDATIONS The acute management of a patient with wide QRS complex tachycardia (WCT) depends on the hemodynamic stability of the patient. Urgent or emergency management is required in unstable patients, with management taking precedence over further diagnostic workup until the patient has been stabilized. Following initial management and stabilization of the patient, chronic management of the patient with WCT will be directed by the etiology of the WCT (supraventricular versus ventricular). (See 'Management' above.) https://www.uptodate.com/contents/wide-qrs-complex-tachycardias-approach-to-management/print 13/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate All patients with a WCT should have a brief immediate assessment of the symptoms, vital signs, and level of consciousness to determine if they are hemodynamic stable or unstable. An unstable patient will have evidence of hemodynamic compromise, such as hypotension, altered mental status, chest pain, or heart failure, whereas a stable patient shows none of these despite a sustained rapid heart rate. (See 'Initial management' above.) While the assessment of hemodynamic status is being performed by a clinician, other members of the health care team should administer supplemental oxygen, establish intravenous access, send blood for appropriate initial studies, attach the patient to a continuous cardiac monitor, and obtain a 12-lead electrocardiogram (ECG). (See 'Initial management' above and "Wide QRS complex tachycardias: Approach to the diagnosis", section on 'Ancillary testing'.) Patients with WCT who are hemodynamically unstable and pulseless, or who become pulseless during the course of evaluation and treatment, should be managed according to standard advance cardiac life support (ACLS) resuscitation algorithms, with immediate high-energy defibrillation and cardiopulmonary resuscitation (CPR) ( algorithm 2). Patients should initially be treated with a synchronized (if possible) 120 to 200 joule shock from a biphasic defibrillator or a 360 joule shock from a monophasic defibrillator. An unsynchronized shock should be delivered if synchronization is not possible [6]. (See 'Unstable patients' above and "Advanced cardiac life support (ACLS) in adults" and "Adult basic life support (BLS) for health care providers".) For patients with WCT who are hemodynamically unstable, but still responsive with a discernible blood pressure and pulse, we recommend urgent cardioversion (with procedural sedation when feasible) (Grade 1A). (See 'Unstable patients' above.) If the QRS complex and T wave can be distinguished, an attempt at emergency synchronized cardioversion can be performed with a synchronized shock of 100 joules using either a biphasic or monophasic defibrillator. If the QRS complex and T wave cannot be distinguished accurately, and a synchronized shock is not possible, we administer an unsynchronized 120 to 200 joule shock from a biphasic defibrillator or a 360 joule shock from a monophasic defibrillator. For hemodynamically stable patients with WCT which is regular and monomorphic in whom the etiology of the WCT remains uncertain, we suggest vagal maneuvers (ie, Valsalva, carotid sinus massage) followed by intravenous adenosine if no response to the vagal maneuvers (Grade 2C). Further treatment is directed by the response to vagal maneuvers and/or adenosine, specifically targeting ventricular tachycardia (VT) or the https://www.uptodate.com/contents/wide-qrs-complex-tachycardias-approach-to-management/print 14/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate relevant supraventricular tachycardia (SVT). If the WCT persists and the etiology remains uncertain, we proceed as though the WCT is VT and treat accordingly. (See 'Stable patients with uncertain WCT etiology' above.) For patients who are hemodynamically stable and known to have VT, some of our experts proceed directly to electrical cardioversion, while others prefer to begin with an intravenous antiarrhythmic agent and reserve cardioversion for refractory patients or for those who become unstable. (See 'Ventricular tachycardia' above.) For patients who are hemodynamically stable and known to have SVT, we suggest the following approach (Grade 2C) (see 'Supraventricular tachycardia' above): If the SVT is likely to be atrioventricular nodal reentrant tachycardia (AVNRT) or atrioventricular reciprocating tachycardia (AVRT), we perform vagal maneuvers, followed by adenosine, followed by intravenous verapamil or diltiazem, and, in refractory cases, electrical cardioversion. If the SVT terminates after any of the interventions, the subsequent interventions are not performed acutely. If the arrhythmia is known to be atrial fibrillation (AF), atrial flutter, or an atrial tachycardia, management options include rate control and cardioversion (ie, rhythm control). (See "Overview of atrial flutter" and "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".) If the WCT is thought to be directly related to the function of pacemaker, the appropriate therapy is the placement of a magnet over the pacemaker. (See 'Patients with a pacemaker' above.) Chronic therapy for patients with WCT will be driven by the underlying etiology of the WCT, with patients having VT generally considered for implantable cardioverter-defibrillator (ICD) implantation, while therapy for patients with SVT will need to be tailored to the underlying arrhythmia. (See 'Chronic therapy' above.) ACKNOWLEDGMENT The UpToDate editorial staff acknowledges 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. https://www.uptodate.com/contents/wide-qrs-complex-tachycardias-approach-to-management/print 15/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate REFERENCES 1. Buxton AE, Marchlinski FE, Doherty JU, et al. Hazards of intravenous verapamil for sustained ventricular tachycardia. Am J Cardiol 1987; 59:1107. 2. Stewart RB, Bardy GH, Greene HL. Wide complex tachycardia: misdiagnosis and outcome after emergent therapy. Ann Intern Med 1986; 104:766. 3. Dancy M, Camm AJ, Ward D. Misdiagnosis of chronic recurrent ventricular tachycardia. Lancet 1985; 2:320. 4. Akhtar M, Shenasa M, Jazayeri M, et al. Wide QRS complex tachycardia. Reappraisal of a common clinical problem. Ann Intern Med 1988; 109:905. 5. Brugada J, Katritsis DG, Arbelo E, et al. 2019 ESC Guidelines for the management of patients with supraventricular tachycardiaThe Task Force for the management of patients with supraventricular tachycardia of the European Society of Cardiology (ESC). Eur Heart J 2020; 41:655. 6. Link MS, Atkins DL, Passman RS, et al. Part 6: electrical therapies: automated external defibrillators, defibrillation, cardioversion, and pacing: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2010; 122:S706. 7. Gupta AK, Thakur RK. Wide QRS complex tachycardias. Med Clin North Am 2001; 85:245. Topic 101641 Version 31.0 https://www.uptodate.com/contents/wide-qrs-complex-tachycardias-approach-to-management/print 16/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate GRAPHICS 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/wide-qrs-complex-tachycardias-approach-to-management/print 17/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate Adult cardiac arrest algorithm https://www.uptodate.com/contents/wide-qrs-complex-tachycardias-approach-to-management/print 18/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate https://www.uptodate.com/contents/wide-qrs-complex-tachycardias-approach-to-management/print 19/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate Reprinted with permission. Highlights of the 2020 American Heart Association Guidelines for CPR and ECC. Copyright 2020 American Association, Inc. Graphic 129983 Version 9.0 https://www.uptodate.com/contents/wide-qrs-complex-tachycardias-approach-to-management/print 20/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate Adult tachycardia with a pulse algorithm 2020 update Reprinted with permission. ACLS Provider Manual. Copyright 2020 American Heart Association, Inc. Graphic 130747 Version 10.0 https://www.uptodate.com/contents/wide-qrs-complex-tachycardias-approach-to-management/print 21/22 7/5/23, 10:41 AM Wide QRS complex tachycardias: Approach to management - UpToDate Contributor Disclosures Peter J Zimetbaum, MD Consultant/Advisory Boards: Abbott Medical [Lead extraction]. All of the relevant financial relationships listed have been mitigated. Ary L Goldberger, MD Other Financial Interest: Elsevier book royalties [Clinical electrocardiography]. All of the relevant financial relationships listed have been mitigated. James Hoekstra, MD No relevant financial relationship(s) with ineligible companies to disclose. 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/wide-qrs-complex-tachycardias-approach-to-management/print 22/22