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2.5 mg boluses), are more effective in reducing the tachycardia rate than in terminating it.97,99,100,128 Although evidence for the effectiveness of beta-blockers in terminating SVT is limited, they have an excellent safety profile in haemodynamically stable patients. Betablockers are contraindicated in patients with decompensated HF. Caution is needed with concomitant use of i.v. calcium channel blockers and beta-blockers, because of possible potentiation of hypotensive and bradycardic effects. In the first clinical trial of etripamil, a short-acting L-type calcium channel blocker with a rapid onset of action after intranasal administration, conversion rates from SVT to sinus rhythm ranged from 6595%.129

10.1.2 Wide QRS (120 ms) tachycardias The acute management of a patient with wide QRS tachycardia depends on the haemodynamic stability of the patient (Figure 5).106,130,131

10.1.2.1 Haemodynamically unstable patients Haemodynamic instability may occur with any wide QRS tachycardia, regardless of the cause, but is more likely in patients with VT. Synchronized cardioversion is recommended for any persistent wide QRS tachycardia resulting in hypotension, acutely altered mental status, chest pain, acute HF symptoms, or signs of shock.86,87 10.1.2.2 Haemodynamically stable patients In a patient with wide QRS tachycardia who is haemodynamically stable, the response to vagal manoeuvres may provide insight into the mechanism responsible for the arrhythmia. SVT with aberrancy, if definitively identified, may be treated in the same manner as narrow complex SVT, with vagal manoeuvres or drugs (adenosine and other AVN-blocking agents such as beta-blockers or calcium channel blockers).117119,129

Some drugs used for the diagnosis or treatment of SVT (e.g. verapamil) can cause severe haemodynamic deterioration in patients with a previously stable VT.64,133,134 Thus, they should only be used for the treatment of patients in whom the diagnosis of SVT is fully established and secure. Adenosine may be helpful by means of allowing a diagnosis or interrupting an adenosine-sensitive VT, but it must be avoided if pre-excitation on resting ECG suggests a pre-excited tachycardia. There is a risk that in antidromic re-entry, adenosine may precipitate cardiac arrest if there is induction of AF by adenosine, as may occasionally occur.135 For pharmacological termination of a haemodynamically stable wide QRS-complex tachycardia of unknown aetiology, i.v. procainamide or amiodarone can be used in-hospital.132,136138 In the PROCAMIO trial132 in patients with well-tolerated wide QRS

Recommendations for the acute management of wide QRS tachycardia in the absence of an established diagnosis

Recommendation Classa Levelb

Haemodynamically unstable patients Synchronized DC cardioversion is recommended in haemodynamically unstable patients.86,130 I B Haemodynamically stable patients A 12 lead ECG during tachycardia is recommended. I C Vagal manoeuvres, preferably in the supine position with leg elevation, are recommended. I C Adenosine should be considered if vagal manoeuvres fail and there is no pre-excitation on a resting ECG. IIa C Procainamide (i.v.) should be considered if vagal manoeuvres and adenosine fail.132 IIa B Amiodarone (i.v.) may be considered if vagal manoeuvres and adenosine fail.132 IIb B Synchronized DC cardioversion is recommended if drug therapy fails to convert or control the tachycardia.86,130 I B Verapamil is not recommended in wide QRScomplex tachycardia of unknown aetiology.64,133,134 III B

DC = direct current; ECG = electrocardiogram; i.v. = intravenous. aClass of recommendation. bLevel of evidence. ©ESC 2019

Wide QRS tachycardia

Vagal manoeuvres

(I C)

i.v. adenosine (if no evidence of pre-excitation on resting ECG)

(IIa C)

i.v. procainamide

(IIa B) i.v. amiodarone

(IIb B) Synchronized cardioversion

(I B)

Yes No

If ineffective

If ineffective

If ineffective Haemodynamic

instability

Figure 5 Acute therapy of wide complex tachycardia in the absence of an established diagnosis. AVRT = atrioventricular re-entrant tachycardia; i.v. = intravenous. Downloaded from academic.oup.com/eurheartj/article/41/5/655/5556821 by guest on 07 October 2026