Abnormal ECG findings in ARVC Over 80% of patients with ARVC will have an abnormal ECG.45 50 51 ECG abnormalities include TWI in the anterior precordial leads, epsilon waves, delayed S wave upstroke, lowvoltage in limb leads and premature ventricular beats with an LBBB morphology and superior axis. If there is primarily LV involvement, the TWI involves the lateral precordial leads and the premature ventricular beats can have an RBBB morphology. T wave inversion TWI in the anterior precordial leads (V1–V3/V4) is present in approximately 85% of patients with ARVC in the absence of RBBB (figures 10 and 11).50 the left precordial leads V5–V6 or inferior limb leads II, III and aVF. TWI in V1–V3 or beyond in individuals >14 years of age (in the absence of complete RBBB) represent a major diagnostic criterion for ARVC, while TWI confined to just leads V1 and V2 in individuals >14 years of age (in the absence of complete RBBB) represents a minor diagnostic criterion.49 In Italian children ≥14 years with TWI in the anterior precordial leads beyond V2 (ie, V3 or V4), 3 of 26 (11%) fulfilled diagnostic criteria for ARVC (1 definitive, 2 borderline).28 In the presence of complete RBBB, right precordial (V1–V3) TWI is more likely secondary to RBBB rather than a sign of underlying ARVC. TWI extending beyond V3 is uncommon in patients with RBBB and represents a minor diagnostic criterion for ARVC.49 Thus, TWI involving at least two consecutive precordial leads, excluding V1, should prompt further investigation in the athlete. Epsilon waves Epsilon waves are defined as distinct low-amplitude potentials localised at the end of the QRS complex. Epsilon waves are challenging to detect and appear as a small negative deflection just beyond the QRS in V1–V3 (figure 10). The presence of epsilon waves in the right precordial leads V1– V3 represents a major diagnostic criterion for ARVC.49 Delayed S wave upstroke Delayed S wave upstroke of >55 ms in leads V1–V3 in the absence of complete RBBB represents a minor diagnostic criterion for ARVC (figure 11).49 This feature is most commonly observed among ARVC patients with mild QRS prolongation (100–120 ms). The S wave upstroke is measured from the nadir of the S wave to the end of the QRS (including epsilon wave if present). Prolonged S wave upstroke Figure 10. ECG from a patient with arrhythmogenic right ventricular cardiomyopathy. (A) Inverted T waves in leads V1–V5. (B) A subtle epsilon wave with notching in V1 at the terminal portion of the QRS complex. TWI occasionally extends to Figure 11. ECG from a patient with arrhythmogenic right ventricular cardiomyopathy showing delayed S wave upstroke in V1 (arrow), low voltages in limb leads <5 mm (circles), and inverted T waves in anterior precordial leads (V1–V4) and inferior leads (III and aVF). may be present in up to 95% of patients with ARVC in the absence of RBBB.50 Low voltage in limb leads Low voltage in limb leads, defined as a QRS amplitude ≤5 mm in each of the limb leads (I, II and III), also can be suggestive of ARVC (figure 11). Premature ventricular contractions Premature ventricular contractions (PVCs) originating from the right ventricle typically show an LBBB pattern with a predominantly negative QRS complex in V1. On the basis of the QRS axis in the limb leads the origin of the PVC can be further suggested. PVCs with LBBB morphology and an inferior axis ( positive in the inferior leads) originate from the nummer 4 | september 2013 | Sport & Geneeskunde 31 Pagina 30
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