Right Ventricular Tachycardia
Common Presentation Versus Common Disease
A 46-year-old man presented to the emergency department with palpitation and chest pain with hemodynamically stable wide complex tachycardia of left bundle-branch block morphology (Figure 1). Electric cardioversion restored sinus rhythm after a trial of intravenous amiodarone (Figure 2A). Echocardiography demonstrated a normal left ventricle (LV); however, the right ventricle (RV) was dilated with contractile dysfunction and regional wall motion abnormalities (Movies I and II in the online-only Data Supplement).There were no valvular abnormalities in Doppler echo evaluation. The estimated pulmonary artery systolic pressure was 31 mm Hg from the tricuspid flow Doppler. The patient was referred for consideration for implantable defibrillator implantation with a diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) with monomorphic ventricular tachycardia (VT).
The cardiac biomarkers were elevated with a creatinine kinase level of 401 U/L (reference value, <225 U/L), and cardiac troponin T levels were 0.6 μg/L (reference value, <0.04 μg/L). These abnormal results were thought to be attributable to a combination of various factors such as the arrhythmia, electric cardioversion, and a previous diagnosis of myopericarditis. Creatinine kinase levels reduced to 124 U/L over the next week of hospitalization, and cardiac troponin T levels were 0.54 μg/L after 1 week of hospitalization.
Two weeks before presentation, he had been hospitalized with a diagnosis of myopericarditis. ECGs were interpreted as normal in the community hospital; however, when the initial ECGs were reviewed, there was subtle evidence of ischemic injury as evidenced by 1-mm ST-segment elevation in inferior leads with the loss of R wave in lead 3, which were not considered abnormal during his initial admission (Figure 2B). A possible diagnosis of acute coronary syndrome was entertained after the ECGs were reviewed.
An MRI scan demonstrated mildly dilated RV (168 mL) with decreased global RV function (ejection fraction 38%) owing to akinesia of the RV free wall extending to the RV inferior wall. There was late gadolinium enhancement of the akinetic segments (Figure 3). The LV was normal (Movie III in the online-only Data Supplement).
Coronary angiogram (Figure 4A through 4D) showed a proximal total occlusion of a dormant right coronary artery, which supplied only the RV (Movies IV and V in the online-only Data Supplement), and percutaneous balloon angioplasty with stent placement was performed (Figure 5E and 5F) to open this vessel (Movies VI through VIII in the online-only Data Supplement). The left system was dominant and free from disease (Movies IX and X in the online-only Data Supplement). The results of the left ventriculogram were normal (Movie XI in the online-only Data Supplement).
After stenting, ECG demonstrated improvement in R-wave amplitude in lead III. There was a 1-mm ST-segment depression, and T-wave inversion, as well (Figure 5).
An electrophysiological study was performed after 4 weeks of revascularization with the electroanatomic 3D CARTO mapping system. Only nonsustained VT could be induced. Bipolar voltage mapping revealed a low-voltage area along the RV free wall region (Figure 6) corresponding with the scar delineated by MRI. Late potentials were ablated, and VT remained noninducible afterward. There has been no recurrence of VT during 18 months of follow-up.
A repeat MRI on follow-up after 1 year revealed significant reduction in the size of gadolinium-enhancing scar of the RV free wall (Figure 7), and cine MRI demonstrated significant improvement of RV function, and almost complete resolution of the wall motion abnormalities, as well (Movie XII). Genetic screening for ARVD mutations was negative. ECG at 1 year follow-up is shown in Figure 8, which is essentially normal with the exception of a leftward axis. There were no pathological Q waves in the ECG to suggest any significant myocardial damage.
It is extremely rare for infarct-related VT to arise from the RV free wall.1 Although more than one-third of VT in ischemic heart disease has left bundle-branch block morphology, most VTs originate in the LV close to the septum. Isolated RV myocardial infarction is also a rare entity. Catheter ablation of postinfarction VT with left bundle-branch block morphology has been reported from the RV after failed ablation attempts from the left side.2 Infarct-related RV VT after an isolated RV myocardial infarction has not been reported before.
ARVC/D is the most common cause of RV free wall VT in a person with a normal LV; however, failure to consider other causes can lead to unnecessary implantation of a defibrillator. This case emphasizes the importance of identifying the subtle signs of ischemia in ECG not to miss a diagnosis of an isolated RV infarction. The RV is not well represented in standard 12-lead ECG; the ECG changes in the RV are likely to be missed in the standard 12-lead ECG. Typically, RV infarction accompanies an inferior wall myocardial infarction, and the clinical presentation is dramatic with hypotension and a diagnosis is hardly missed.
MRI findings in ARVC/D can, to a certain extent, mimic those in ischemic heart disease. However, the abnormalities in ARVC/D show progression over time in comparison with changes secondary to myocardial infarction.3 A reduction in the scar size and improvement in ventricular function after revascularization of the culprit artery is confirmatory evidence that insult is ischemic rather than a primary myocardial abnormality as in ARVC/D.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIRCULATIONAHA.112.001159/-/DC1.
- © 2013 American Heart Association, Inc.
- Masci PG,
- Francone M,
- Desmet W,
- Ganame J,
- Todiere G,
- Donato R,
- Siciliano V,
- Carbone I,
- Mangia M,
- Strata E,
- Catalano C,
- Lombardi M,
- Agati L,
- Janssens S,
- Bogaert J