Kharbanda RK, Moore JP, Lloyd MS, Galotti R, Bogers AJJC, Taverne YJHJ, Madhavan M, McLeod CJ, Dubin AM, Mah DY, Chang PM, Kamp AN, Nielsen JC, Aydin A, Tanel RE, Shah MJ, Pilcher T, Evertz R, Khairy P, Tan RB, Czosek RJ, Shivkumar K, de Groot NMS.J Am Heart Assoc. 2022 Nov 15;11(22):e025121. doi: 10.1161/JAHA.121.025121. Epub 2022 Nov 8.PMID: 36346046
Commentary from Dr. M.C. Leong (Kuala Lumpur, Malaysia), section editor of ACHD Journal Watch:
Take Home Points:
- In the short term, CTR improves NYHA functional class in patients with systemic right ventricle without improving the ejection fraction of the ventricles.
- In the long term, there is a decrease in QRS duration and improvement in NYHA functional class in patients with pre-CRT ventricular pacing. The same is not seen in patients without pre-CRT ventricular pacing.
- In patients with CRT, diabetes, hypertension, the lack of improvement in NYHA class, and basal segment SRV lead position were associated with increased risk of heart failure associated admission.
Cardiac resynchronization therapy (CRT) improves mechanical synchrony between the right and left ventricle with the aim to improve symptoms, heart failure control and mortality. While its use in the systemic left ventricle has shown promising results, its benefits in the systemic right ventricle (SRV) in the congenital heart disease realm have only been supported by small studies, some of which were heterogeneous in their study populations, obviating any strong conclusion. This was a commendable effort by the team from 13 centres across the United States, Canada and Europe investigating both early and late outcomes of CRT in patients with an SRV and identifying predictors for congestive heart failure readmissions and mortality. Importantly, the team only included patients who had congenitally corrected transposition of the great arteries (CCTGA) and dextro-transposition of the great arteries (D-TGA) post-atrial switch operation, eliminating heterogeneity in its study population.
80 patients [48.9% women, mean age of 45±14 years at the initiation of CRT, 63 (78.8%) CCTGA and 17 (21.3%) D-TGA] were followed for a median duration of 4.1 (range, 1.3–8.3) years. The average QRS duration was 161±36 ms (range, 82–240), and 38.8% of the patients were in NYHA functional class III/IV. The ventricular function was moderately or severely impaired in 83% of patients. The majority (70%) of the patients received a CRT-defibrillator device. SRV lead position (available in 78 [97.5%] patients) was near the outflow tract in 6 (7.7%), basal segment in 21 (26.9%), mid segments in 35 (44.9%), and near the apex in 16 (20.5%)
Short-term (<6 moths) outcomes showed significant improvements in QRS duration and NYHA class for patients with pre-CRT ventricular pacing but without a significant improvement in ejection fraction (EF). Patients without ventricular pacing had QRS prolongation but improved NYHA class without EF improvement. (Table 1)
Long-term outcomes demonstrated a significant reduction in QRS duration, improved NYHA class, and a slight increase in EF for patients with pre-CRT ventricular pacing. However, patients without ventricular pacing had no improvement in EF or NYHA class and an increase in QRS duration. At the latest follow-up, 46% of patients were in NYHA class III/IV. (Table 2)
Comparison between patients with CCTGA and D-TGA revealed no significant differences in baseline characteristics or long-term outcomes, except for short-term QRS duration. The type of CRT system (transvenous vs. epicardial/mixed) did not significantly affect outcomes.
During the follow-up period, 26% of patients were readmitted for congestive heart failure. Diabetes, hypertension, the lack of improvement in NYHA class, and basal segment SRV lead position were associated with increased risk of readmission. (Table 3) The mortality rate was 7.5% at 5 years and increased to 21.3% at the latest follow-up. (Figure 1) There were no significant differences in survival based on the type of congenital heart defect or pre-CRT ventricular pacing. (Table 4)
The study emphasises that patients with SRV, but not those without, benefit from upgrading their pre-existing ventricular pacing to CRT. Despite the lack of an apparent long-term benefit from CRT, the study’s findings can be taken in one of two ways: either there is no apparent long-term benefit from CRT, or it maintains stable heart function and functional status. So, which of the two is your stance?
