The electrocardiographic morphology of the VT/PVCs has been used to differentiate the two entities. Multiple VT forms including LBBB/superior axis essentially excludes RVOT-VT and should shift your pre-test probability toward ARVD/C (Arbelo and Josephson, 2010
). An example of LBBB/superior axis VT from an ARVD/C patient is shown in Figure .
LBBB/superior axis VT from a patient with ARVD/C.
Ainsworth et al. (2006
) analyzed QRS duration to help differentiate ARVD/C from RVOT-VT. They found that mean QRS duration was longer in all 12 leads in ARVC patients with a significant difference seen in leads I, III, aVL, aVF, V1, V2, and V3 (p
0.05). Leads I and aVL had the largest mean difference between ARVC and RVOT-VT patients of 17.6
4.7 and 15.8
ms, respectively (p
0.0001). Lead I QRS duration ≥120
ms had a sensitivity of 100%, specificity 46%, positive predictive value 61%, and negative predictive value (NPV) 100% for ARVC.
More recently we found several ECG criteria helpful in distinguishing between ARVD/C and RVOT-VT (Hoffmayer et al., 2011
). ARVD/C patients had a significantly longer mean QRS duration in lead I (150
31 versus 123
0.006), more often exhibited a precordial transition in lead V6 [3/17 (18%) versus 0/42 (0%) with RVOT-VT, p
0.005] and more often had at least one lead with notching [11/17 (65%) versus 9/42 (21%), p
0.001]. The most sensitive characteristics for the detection of ARVD/C was a QRS duration in lead I of ≥120
ms (sensitivity 88%, NPV 91%). QRS transition at V6 was most specific 100% (PPV 100%, NPV 77%). In multivariate analysis, QRS duration in lead I
ms (OR 20.4, p
0.034), earliest onset QRS in lead V1 (OR 17.0, p
0.022), QRS notching (OR 7.7, p
0.018), and a transition V5 or later (OR 7.0, p
0.030) each predicted an increased odds of ARVD/C. Figure shows examples of these findings.
Figure 2 Ventricular tachycardia morphology characteristics (Hoffmayer et al., 2011). Twelve lead ECGs from patients with RVOT-VT (A–C) and ARVD/C (D–H) showing characteristic features. (A) RVOT-VT from anterior–septal location, showing (more ...)