SPC365

A nearly misdiagnosed wide complex tachycardia: all algorithms have flaws

Session: Sessão Speaker’s Corner - Casos Clínicos desafiantes… em Arritmologia
Speaker: Joana Silva Ferreira

Congress: CPC 2022
Topic: C. Arrhythmias and Device Therapy
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Session Type: Sessão de Casos Clínicos
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Authors: Joana Silva Ferreira; Leonor Parreira; Marta Fonseca; Dinis Mesquita; José Maria Farinha; Ana Fátima Esteves; Rui Coelho; Rui Caria
<p><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif"><strong>Introduction</strong>:&nbsp;</span></span><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">Wide-QRS tachycardia is a common presentation in the Emergency Department (ED).&nbsp;Although differentiating between supraventricular and ventricular tachycardia (VT)&nbsp;is critical for an appropriate treatment, it can still prove quite challenging. Clinicians usually make this distinction based on clinical context and several ECG criteria and algorithms. </span></span></p>

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<p><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif"><strong>Case</strong>:&nbsp;&nbsp;</span></span><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">A 55-year-old man with no prior medical history is referred to a Cardiology consult from the&nbsp;ED&nbsp;for VT. </span></span><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">He had presented to the ED, hemodynamically stable, with palpitations and light-headedness.</span></span><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">&nbsp;ECG showed a wide-QRS regular tachycardia with a ventricular rate of 250 bpm, right bundle branch block morphology and extreme axis deviation (Fig.&nbsp;1A).</span></span></p>

<p><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">Vagal manoeuvres and adenosine (6+12+18 mg) had been administered, with no response, including no change in ventricular rate.</span></span><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">&nbsp;</span></span><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">His blood tests were unremarkable but echocardiography showed a dilated and diffusely hypokinetic left ventricle with an ejection fraction (LVEF) of 32% and a dilated left atrium. VT was assumed as most likely diagnosis and a&nbsp;</span></span><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">perfusion of amiodarone was initiated. Under amiodarone,&nbsp;the wide-QRS tachycardia ceased and&nbsp;the patient presented an atrial flutter (AFL)&nbsp;with narrow QRS at a rate of 125 bpm (Fig. 1B), before finally cardioverting to sinus rhythm. The ECG in sinus rhythm had normal atrioventricular (AV) and intraventricular conduction and no evidence of pre-excitation.</span></span></p>

<p><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">Comparing the first two&nbsp;ECGs, we noticed that the wide QRS tachycardia had exactly twice the rate of the AFL and, reviewing the first ECG, we also found&nbsp;flutter waves at 250 bpm without AV dissociation, which established the diagnosis of AFL&nbsp;with 1:1 conduction.</span></span></p>

<p><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">Electrophysiologic study elicited a typical AFL and cavotricuspid isthmus ablation was performed. No sustained ventricular arrhythmias were induced nor were there accessory pathways.&nbsp;</span></span><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">Cardiac MRI excluded fibrosis. The systolic dysfunction was assumed secondary to tachycardia-induced cardiomyopathy and the patient was discharged on direct oral anticoagulants and neurohormonal medication. Echocardiographic reassessment after ablation demonstrated a recovering LVEF.</span></span></p>

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<p><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif"><strong>Discussion:&nbsp;</strong></span></span><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">We report a case of AFL presenting as a wide-QRS tachycardia, initially misdiagnosed as VT based on&nbsp;its&nbsp;complete non-responsiveness to adenosine, the context of LV dilation and dysfunction as well as some of the ECG&rsquo;s features.&nbsp;In fact, the Brugada and limb lead&nbsp;algorithms would also diagnose this tachycardia&nbsp;as VT.&nbsp;</span></span></p>

<p><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif">This case reminds us that ECG diagnostic algorithms have flaws and that a meticulous analysis of the ECG before, during&nbsp;and after treatment is imperative&nbsp;since subtle features can be essential clues to the right diagnosis. It is also a reminder that, although wide-QRS tachycardia in the setting of LV&nbsp;dysfunction is most often VT,&nbsp;sometimes the systolic dysfunction is not the origin but rather the consequence of the tachycardia.</span></span></p>