Sudden Death Risk in Congenitally Corrected Transposition With Ventricular Dysfunction: Patient case submitted by Matthias Greutmann, MD, FESC

Case Synopsis

We report the case of a patient diagnosed with congenitally corrected transposition of the great arteries (ccTGA) at the age of 1 year. He developed severe systemic tricuspid valve regurgitation at the age of 6 years when it was decided to perform a double switch operation to prevent systemic right ventricular (RV) failure. As preparation for the double switch procedure, to “train” the subpulmonic left ventricle (LV), progressive pulmonary artery banding (PAB) was performed in two stages over a 3-month period. At this point, systolic pressures in the subpulmonic LV had risen to about 90% of systemic pressures, and due to the shift of the interventricular septum and improved tricuspid valve geometry, the degree of tricuspid regurgitation (TR) had improved from severe to mild.

Although LV ejection fraction (EF) was noted to be mildly impaired (45%–50%), a double switch operation was performed. The postoperative course was complicated by rapid, progressive systemic LV failure, requiring escalation of medical therapy. For persistent LV dysfunction despite a narrow QRS width of 96 ms, the patient underwent implantation of biventricular epicardial pacemaker (CRT-P) in 2005 at the age of 9 years ( Fig. 1.1 ). No improvement of LVEF or exercise capacity was noted after pacemaker implantation.

At the age of 16 years, a new pacemaker system was implanted due to electrode dysfunction. Between the age of 10 and 18 years he had recurrent episodes of intraatrial reentrant tachycardia, requiring multiple direct current cardioversions and ablation procedures. When the patient was transitioned to adult care at the age of 18 years he remained in heart failure with NYHA functional class III and had undergone his last electrical cardioversion 3 weeks prior to transition. Transthoracic echocardiography showed a grossly dilated LV with severely impaired EF below 20%. Resting ECG showed broad QRS complexes with QRS duration of 188 ms, and on pacemaker interrogation, he was noted to be 43% atrial and 100% biventricular paced. As there had been growing evidence of lack of effectiveness of biventricular pacing in patients with narrow QRS complexes since the implantation of the device, it was decided to discontinue pacing and the pacemaker was reprogrammed to VVI 30-mode. ECGs on biventricular pacing and without pacing are displayed in Fig. 1.2 . The QRS duration of native QRS complexes was 98 ms. After reprogramming of the pacemaker and intensification of medical heart failure therapy, symptoms of exercise intolerance improved (increase in peak VO ₂ from 13.1 to 20.4 mL/kg/m ² ), NT-ProBNP levels decreased (from 1544 to 356 ng/L), and LVEF mildly improved (from <20% to around 30%).

Despite persistent severely impaired LV function, it was decided not to implant an AICD for primary prevention at this time due to stenosis of the superior vena cava baffle and uncertain risk-benefit ratio. Because modification of pacemaker programming and modification of medical heart failure therapy, the patient had remained clinically stable in NYHA functional class II without recurrence of sustained arrhythmias during a follow-up of 27 months.