Letter by Thomas et al Regarding Article, “Electrocardiographic Features of Arrhythmogenic Right Ventricular Dysplasia”
To the Editor:
We read with particular interest the study by Jain et al1 in which they state that one of the goals of their study was to develop ECG criteria for arrhythmogenic right ventricular dysplasia that can be used in patients with and without a right bundle-branch block pattern presumably to aid in the diagnosis of the disease. The ECG is probably the first study to be done in a patient with suspected arrhythmogenic right ventricular dysplasia and probably the one with least interobserver variability among the panoply of tests often performed in these patients. Hence, the attempt by the authors to refine criteria for the ECG, a ubiquitous diagnostic tool, is laudable.
We are concerned that the control group included 27 patients evaluated in their clinic because of a first- or second-degree relative with arrhythmogenic right ventricular dysplasia. Because all the diagnostic tests were normal, arrhythmogenic right ventricular dysplasia was ruled out, and the subjects were classified as “normal” and included in the control group. Kies et al2 have shown that serial evaluation of suspected cases may be required because some patients who initially do not satisfy Task Force criteria may eventually develop abnormalities, so the inclusion of first- and second-degree relatives of probands in the control group is probably inappropriate in our opinion because it is unclear whether these patients underwent >1 comprehensive evaluation to surely exclude the eventual evolution of clinical abnormalities.
Because these patients are included in the registry for some time, it is also likely that the phenotypic manifestations of the disease, including ECG manifestations, may be more severe compared with newly and recently diagnosed cases as reported recently in the results from the North American Multidisciplinary Study (NAMS).3 Lending credence to this possibility is the difference noted in the abnormalities in the ECG in the group without complete or incomplete right bundle-branch block evaluated by Jain et al (n=68) and the findings of NAMS (n=95) (because the ECG was evaluated in this latter cohort only in the absence of right bundle-branch block). T-wave inversion in V1 through V3, T-wave inversion beyond V3, and QRS prolongation >110 ms also occurred more frequently in the registry compared with NAMS (71% versus 16%, 51% versus 32%, and 43% versus 5%, respectively). Signal-averaged ECG late potentials (74% versus 58%), left bundle-branch block ventricular tachycardia (68% versus 33%), and Holter with premature ventricular contractions >1000/24 hours (68% versus 57%) were also more frequent in the registry. Whereas only 10% of patients in the NAMS cohort had complete right bundle-branch block on the ECG, 17% in the Hopkins cohort had complete right bundle-branch block, and these patients were more likely to have severe right ventricular dilatation and a decrease in right ventricular ejection fraction.
We feel that the ECG criteria that the authors published are probably phenotypic manifestations of the more advanced forms of the disease, which can be diagnosed from the presence of multiple abnormalities on various tests. Therefore, the value of the criteria presented by Jain et al in evaluating patients with disease suspected for the first time may be limited in most general cardiology practices.
Jain R, Dalal D, Daly A, Tichnell C, James C, Evenson A, Jain R, Abraham T, Yew Tan B, Tandri H, Russell SD, Judge D, Calkins H. Electrocardiographic features of arrhythmogenic right ventricular dysplasia. Circulation. 2009; 120: 477–487.
Kies P, Bootsma M, Bax JJ, Zeppenfeld K, van Erven L, Wijffels MC, van der Wall EE, Schalij MJ. Serial reevaluation for ARVD/C is indicated in patients presenting with left bundle branch block ventricular tachycardia and minor ECG abnormalities. J Cardiovasc Electrophysiol. 2006; 17: 586–593.
Marcus FI, Zareba W, Calkins H, Towbin JA, Basso C, Bluemke DA, Estes NAM III, Picard MH, Sanborn D, Thiene G, Wichter T, Cannom D, Wilber DJ, Scheinman M, Duff H, Daubert J, Talajic M, Krahn A, Sweeney M, Garan H, Sakaguchi S, Lerman BB, Kerr C, Kron J, Steinberg JS, Sherrill D, Gear K, Brown M, Severski P, Polonsky S, McNitt S. Arrhythmogenic right ventricular cardiomyopathy/dysplasia clinical presentation and diagnostic evaluation: results from the North American Multidisciplinary Study. Heart Rhythm. 2009; 6: 984–992.