CASE PRESENTATION
A 79‐year‐old man with dilated cardiomyopathy was hospitalized for the
treatment of ventricular tachycardia (VT) with syncope. Echocardiography
revealed diffuse mild hypokinesis of the left ventricle (LV) with an
ejection fraction of 45%. Cardiac magnetic resonance imaging identified
non-specific fibrosis in the LV posterior wall, but no right ventricular
abnormality was apparent. Coronary angiography showed no significant
coronary artery stenosis (Fig. 1A). Radiofrequency catheter ablation
(RFCA) was performed with intravenous midazolam, morphine, and
acetaminophen. The baseline surface electrocardiogram showed atrial
fibrillation with complete right bundle branch block and left axis
deviation (Fig. 2A) as well as frequent runs of non-sustained VT (VT 1)
(Fig. 3A). The morphology of VT 1 was a left bundle branch block pattern
with a precordial transition in lead V4 and inferior axis. The
activation map of VT 1 showed a centrifugal pattern from the septal
aspect of the right ventricular outflow tract (RVOT), which was targeted
with RFCA (irrigated tip catheter, maximum power 35 W) (Fig. 1B).
Maximum contact force exceeded 50 g at some RFCA sites. VT 1 was
suppressed after 180 seconds of RFCA; however, other VTs (VT 2 and VT 3)
occurred thereafter (Fig. 3B and 3C). The morphologies of VT 2 and VT 3
were similar to that of VT 1, but the precordial transition occurred in
lead V3. The initiations of these VTs were accompanied by an
acceleration in heart rate, and no preceding ventricular premature beats
were observed. Additional RFCA was performed in the RVOT, targeting the
earliest local ventricular potentials during the VTs. However, the
frequency and duration of VTs only increased. At this point,
ST-elevation in the precordial leads and in aVL was noted (Fig. 2B). A
review of surface electrocardiograms revealed that ST-elevation appeared
4 minutes after RFCA for VT1, but the patient had remained asymptomatic.
Coronary angiography confirmed a total occlusion of the mid left
anterior descending artery (LAD) (Fig. 1C), which was treated with
emergency coronary angioplasty. Following reperfusion, all VTs
completely resolved. Merging three-dimensional computed tomography
images with electroanatomical maps revealed that the RFCA sites were
markedly close to the mid LAD (Fig. 1C). No VT recurrence was observed
during six months’ follow-up.