The interesting ECG

A “hidden” ECG abnormality …

DOI: https://doi.org/10.4414/cvm.2020.02134
Publication Date: 07.11.2020
Cardiovasc Med. 2020;23:w02134

Vivekanantham Hari, Graf Denis

Department of Cardiology, University and Hospital of Fribourg, Fribourg, Switzerland

Case presentation

A 52-year-old Caucasian man was referred to our cardiology consultation by his general physician for work-up. The patient had no particular symptoms, but family history was relevant for his 28-year-old nephew’s (the son of his brother) recent death of undetermined cause. Additionally, his 60-year-old other brother recently underwent an implantable cardioverter-defibrillator (ICD) implantation for an “abnormal looking” ECG, according to the patient. A physical examination and transthoracic echocardiography were unremarkable. The following electrocardiogram (ECG) (Figure 1) was obtained.

fullscreen
Figure 1
ECG on presentation.

What is your diagnosis? What would be your next step(s) in managing this patient?

Solution

There is a regular sinus rhythm with a frequency of 68 bpm and a normal axis (30°). The PR segment and QRS complex width are in the normal range, with values of about 180 ms and 110 ms respectively. The presence of an S wave in I, V5 and V6 with an rSR’ appearance of the QRS in V1 denotes an incomplete right bundle branch block (IRBB). There is evident 0.5 to 1 mm descending ST segment elevation in the lead V1, with the presence of a negative T wave in the same lead. The corrected QT interval is normal and calculated at 419 ms.

The described IRBB and repolarization abnormality in V1 could, in the setting of the patient’s family history, suggest a Brugada syndrome (BrS).

BrS consists of a channelopathy. The most commonly involved mutation is that of the SCN5A gene, which codes for a subunit of the cardiac sodium channel [1]. The mutation is transmitted in an autosomal dominant fashion, with variable penetrance and expressivity and with higher prevalence of BrS in males. Typically, no structural cardiac abnormalities are found. Patients presenting with this syndrome carry an increased risk of sudden cardiac death (SCD) due to sustained ventricular arrhythmias (VA), which can be enhanced by situations such as increased vagal tone, fever or usage of various drugs. Three types of ECG patterns which can suggest underlying BrS have been described. Type I, or the “coved-type”, consists of a ≥2 mm ST segment elevation in any of V1 to V3, with a concave or straight ST segment followed by a negative T wave. In type II, or the “saddle-back-type”, the ST elevation is ≥0.5 mm in any of V1 or V2, with a convex ST segment followed by a positive T wave in V2. Finally, in the type III pattern, the ST segment elevation is <1 mm and can be either “coved-type”, “saddle-back-type” or both [2]. In order to diagnose BrS, evidence of a spontaneous or inducible type I pattern is required. The 2013 expert consensus proposed that ECG criteria alone were sufficient to make the diagnosis, with additional clinical features (i.e. evidence of VA, history of syncope) being unnecessary [3].

Our patient presents with an ECG suggesting a type III Brugada pattern, and additionally has a positive family history for a nephew dying from sudden (cardiac) death, and a brother having had an ICD implanted, possibly in the setting of a BrS. After exclusion of conditions that can mimic a Brugada-like ECG pattern (i.e. pectus excavatum, right bundle branch block, left ventricular hypertrophy, arrhythmogenic right ventricular cardiomyopathy, ischemia secondary to occlusion of the left anterior descending artery) [1], the next step should be to perform a provocative drug test using a type I antiarrhythmic drug in order to unmask the diagnostic type I pattern. Ajmaline is one type of sodium channel blocker that is commonly used for this purpose. Figure 2 shows the ECG obtained in our patient after infusion of 40 mg of i.v. ajmaline (protocol: i.v. infusion of up to 1 mg/kg over five minutes). Widening of the QRS and ≥2 mm ST segment elevation in V1 to V3 can be distinguished in this ECG, and thus the unmasking of a type I Brugada pattern can be seen, confirming the diagnosis of BrS.

fullscreen
Figure 2
ECG obtained after 40 mg i.v. infusion of ajmaline.

As per the 2015 ESC guidelines for the management of patients with VA and the prevention of SCD [3], the patient was provided with some advice concerning lifestyle: avoidance of a variety of drugs (a complete list can be found at www.brugadadrugs.org), avoidance of large meals or excessive alcohol intake, and immediate treatment of any fever with appropriate medication. As a next step, patients with BrS should undergo risk stratification for eligibility for ICD therapy, which remains the primary treatment option [1]. History of aborted SCD or documented VA undoubtedly qualifies a patient for ICD therapy as for secondary prevention of SCD [2]. In other situations (i.e. nonvagal syncope, seizures, nocturnal agonal respiration), indication for ICD remains controversial, and this is even more so in patients lacking a spontaneous type I pattern. In asymptomatic individuals, ICD implantation may be considered upon the inducibility of VA during an electrophysiological study. In the real-world practice, however, the use of this stratification tool is debated, and hence left to the discretion of the expert centers and to the electrophysiologist’s own judgement. It is important to note that the presence of SCD in a first-degree relative does not, per se, imply an increased risk of SCD in a patient with an asymptomatic BrS.

On additional history taking, our patient reported having passed out a year earlier following alcohol consumption, which can suggest a triggered VA. However, so far no VA that would provide a clear-cut indication for an ICD, has been documented. The patient was presented with the different treatment options, including “watchful waiting” and treatment with quinidine, a class IA antiarrhythmic drug, as an alternative to ICD implantation [4]. In accordance with the patient’s preference, a subcutaneous ICD was finally implanted, as no requirement for cardiac pacing was expected [5]. The patient was referred for genetic testing, and screening of all first-degree relatives was advised.

Disclosure statement

No financial support and no other potential conflict of interest relevant to this article was reported.

Correspondence

Correspondence, Hari Vivekanantham, MD, Department of Cardiology, University and Hospital of Fribourg, Chemin des Pensionnats 2-6, CH-1708 Fribourg, hari.vivekanantham[at]h-fr.ch

References

1 Brugada J, Campuzano O, Arbelo E, Sarquella-Brugada G, Brugada R. Present Status of Brugada Syndrome: JACC State-of-the-Art Review. J Am Coll Cardiol. 2018;72(9):1046–59. doi:. http://dx.doi.org/10.1016/j.jacc.2018.06.037 PubMed

2 Mizusawa Y, Wilde AA. Brugada syndrome. Circ Arrhythm Electrophysiol. 2012;5(3):606–16. doi:. http://dx.doi.org/10.1161/CIRCEP.111.964577 PubMed

3 Priori SG, Blomström-Lundqvist C, Mazzanti A, Blom N, Borggrefe M, Camm J, et al.; ESC Scientific Document Group. 2015 ESC guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J. 2015;36(41):2793–867. doi:. http://dx.doi.org/10.1093/eurheartj/ehv316 PubMed

4 Brodie OT, Michowitz Y, Belhassen B. Pharmacological Therapy in Brugada Syndrome. Arrhythm Electrophysiol Rev. 2018;7(2):135–42. doi:. http://dx.doi.org/10.15420/aer.2018.21.2 PubMed

5 Poole JE, Gold MR. Who should receive the subcutaneous implanted defibrillator?: The subcutaneous implantable cardioverter defibrillator (ICD) should be considered in all ICD patients who do not require pacing. Circ Arrhythm Electrophysiol. 2013;6(6):1236–44, discussion 1244–5. doi:. http://dx.doi.org/10.1161/CIRCEP.113.000481 PubMed

Verpassen Sie keinen Artikel!

close