Author + information
- Received October 3, 2018
- Revision received October 23, 2018
- Accepted October 24, 2018
- Published online February 18, 2019.
- Robert D. Anderson, MBBSa,b,∗,
- Cuneyt Ada, MBBSc,∗,
- Geoffrey Lee, MBChB, PhDa,b,
- Jonathan M. Kalman, MBBS, PhDa,b,
- Jitendra K. Vohra, MDa,b and
- Saurabh Kumar, BS(Med), MBBS, PhDc,d,∗ ()
- aDepartment of Cardiology, Royal Melbourne Hospital, Melbourne, Australia
- bFaculty of Medicine, Dentistry, and Health Science, University of Melbourne, Melbourne, Australia
- cDepartment of Cardiology, Westmead Hospital, Westmead, Australia
- dWestmead Applied Research Centre, University of Sydney, Sydney, Australia
- ↵∗Address for correspondence:
Assoc. Prof. Saurabh Kumar, Department of Cardiology, Westmead Hospital, Westmead Applied Research Centre, University of Sydney, Darcy Road, Westmead, New South Wales 2145, Australia.
Idiopathic ventricular fibrillation (IVF) is a rare and life-threatening arrhythmia. Typically, IVF is initiated by premature ventricular complexes (PVC) emanating from the Purkinje system (PS). Rarely, PVC-triggered ventricular fibrillation (VF) originates from a distant myocardial site and is unrelated to the PS. We describe VF storm in a young man whose triggered, deep myocardial PVCs were successfully treated with emergency catheter ablation.
The index presentation is of VF storm in a healthy and otherwise well 17-year-old adolescent boy with no relevant family history of sudden death who collapsed suddenly while attending a class at school. VF was recorded by a school automated external defibrillator, and multiple external shocks were needed to restore sinus rhythm. Despite antiarrhythmic therapy and intubation, he continued to have episodes of short-coupled PVC-triggered VF (Figures 1A, asterisk, 1B). A high burden of monomorphic PVCs (Figure 1A, arrows) and short bursts of ventricular tachycardia (VT) were seen with a right bundle branch and left superior axis configuration, with positive precordial concordance (Figure 1C, arrows) suggesting a basal-posterior left ventricular (LV) exit. Lidocaine and amiodarone had minimal effect on suppressing ectopy, as did transition to oral nadolol.
A 12-lead electrocardiogram (10 days after cardiopulmonary resuscitation and intensive care unit discharge) was noteworthy for early repolarization (ER) with inferior lead J-point elevation without a Brugada pattern (despite high precordial lead placement) or a prolonged QTc interval (Figure 1C). No polymorphic or bidirectional ectopy was seen. Transthoracic echocardiography revealed a structurally normal heart and preserved biventricular function. Cardiac magnetic resonance (CMR) imaging showed no acute inflammation or edema or late gadolinium enhancement, despite early suspicion of focal myocarditis given a markedly elevated troponin of 8 ng/l (normal reference <0.05 ng/l), which rapidly normalized, and serial levels were negative (Figure 1G, Online Videos 1 and 2). Features of arrhythmogenic right ventricular dysplasia were absent (Figure 1G, Online Video 3). Coronary computed tomography (CT) showed normal coronary origins, luminography, and no arterial embolism, and findings of a septal right ventricular biopsy were negative for inflammatory, infiltrative disease (including sarcoidotic features). CMR, CT, and transthoracic echocardiography did not reveal an LV aneurysm. Positron emission tomography with CT was not performed because CMR did not demonstrate scar or inflammation.
He continued to have clinical ectopy with periods of sustained VT, prompting catheter ablation (Figures 1D and 1E). CT-integrated electroanatomic mapping (CARTO, Biosense Webster, Diamond Bay, California) demonstrated normal unipolar (cutoffs of 6.7 and 8.27 mV) and bipolar LV voltages (Figure 1F). Activation maps of the isoproterenol-precipitated PVC focus were localized to the basal-posteroseptal left ventricle (19 ms pre-QRS complex) (Figure 1G, Online Video 4). At the site of ablation, there were no Purkinje potentials; moreover, the site was well away from the mitral valve and the posterior papillary muscle (Figure 1G). Mapping of sites to the earliest sites of PVC activation did not demonstrate significant abnormalities in sinus rhythm beats (Figure 1G) (sinus rhythm [SR]).
During radiofrequency ablation, tissue contact and location were guided by intracardiac echocardiography (ICE). Once again, no aneurysm formation or localized tissue abnormality was seen on ICE in this region. Despite 10 to 20 g of contact force and 30 to 50 W of irrigated radiofrequency ablation for 30 to 60 s using a Smart-Touch Surround Flow catheter (Biosense Webster), there was transient PVC abolishment, only to return within 1 min of waiting time. PVCs were eventually abolished with multiple lesions at 50 W for 60 to 90 s, until echo brightness was seen within the intramural LV layers on ICE (Figure 1G, inset; Online Video 5). A dual-chamber defibrillator was implanted, and he was discharged on low-dose propranolol (40 mg twice daily), which was discontinued 6 weeks later. Results of provocative testing for concealed channelopathies, off all drugs (sprint exercise stress test for long QT syndrome, epinephrine challenge for catecholaminergic polymorphic VT, and flecanide challenge for Brugada syndrome), were all negative.
He remains free of arrhythmia at 2-year follow-up. Multiple repeat exercise stress tests were performed off propranolol and showed absence of ventricular ectopy or features of catecholaminergic polymorphic VT or long QT syndrome. Both parents have had extensive phenotypic investigations for structural heart disease and channelopathies, and results have been negative. His family is reluctant to have genetic testing.
PVC-triggered VF in patients without structural heart disease is rare, but it is typically seen in patients with IVF or inherited arrhythmic syndromes. Inducing PVCs most commonly originate from the Purkinje system, as confirmed by a characteristic early sharp, pre-PVC potential (1). However, other common sites of origin include the right ventricular outflow tract, papillary muscles, or other low-voltage areas unrelated to Purkinje activity (2). A focus produced from ventricular myocardium is unusual, but isolated cases are reported in patients with long QT syndrome and ER (3). The absence of an obvious phenotype for a primary channelopathy makes this case unique, although ER is most likely. This case demonstrates the efficacy of catheter ablation for PVC-mediated VF, even in the rare instance of deep intramyocardial foci.
↵∗ Drs. Anderson and Ada contributed equally to this work and are joint first authors.
Dr. Anderson has reported support by postgraduate scholarships co-funded by the National Health and Medical Research Council (NHMRC) and the Royal Australasian College of Physicians NHMRC Woodcock Scholarships. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Katja Zeppenfeld, MD, served as Guest Editor for this paper.
All authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the JACC: Clinical Electrophysiology author instructions page.
- Received October 3, 2018.
- Revision received October 23, 2018.
- Accepted October 24, 2018.