Latus H, Stammermann J, Voges I, Waschulzik B, Gutberlet M, Diller GP, Schranz D, Ewert P, Beerbaum P, Kühne T, Sarikouch S; German Competence Network for Congenital Heart Defects Investigators *.J Am Heart Assoc. 2022 Apr 5;11(7):e022694. doi: 10.1161/JAHA.121.022694. Epub 2022 Mar 18.PMID: 35301850
Commentary from Dr. Thomas Zellers (Dallas, USA), section editor of Congenital Heart Disease Interventions and ACHD Journal Watch:
Introduction and summary:
The aim of the study was to assess the hemodynamic impact and prognostic relevance of RV pressure load in a population of patients following tetralogy of Fallot repair. Patients were older than 8 years of age at the time of evaluation with a CMR, echo and exercise stress test. There was no evaluation with initial post-operative RVOT gradient nor was there longitudinal hemodynamic evaluation. There was follow up information on adverse events (ventricular tachycardia or death) and pulmonary valve replacement. Below is the study population algorithm:
Two hundred and ninety-six patients had complete data. Peak RVOT gradients were positively correlated with a) smaller RV volumes b) less pulmonary regurgitation c) lower RV and LV longitudinal systolic strain by echo and d) lower early diastolic strain rates by echo. A trend toward reduced exercise capacity was also found.
Using univariable Cox regression analysis, the authors looked at prognostic relevance of RVOT gradients on the primary endpoints of death (n=6), sustained VT (n=2) and non-sustained VT (n=11). Higher RVOT gradients were significantly associated with these combined primary endpoints. Other predictors are shown in Table 2 below. Further, a RVOT peak gradient > 25 mmHg was associated with a > 3-fold increase in adverse cardiovascular events (HR 3.69, P=0.005) as seen in Figure 3. A second univariable Cox proportional hazard analysis that considered only death or sustained VT as showed a significant relationship with those two endpoints. A comparison between patients with RVOT peak gradients < 25
mmHg vs > 25 mmHg, revealed a much higher risk for these two endpoints in patients with higher gradients (HR 17.9, p= 0.007). A separate subgroup analysis looking at peak gradient and degree of PR was conducted. Peak gradients > 25 mmHg and moderate PR (not severe PR) also had a significant increase in combined adverse events.
Bivariable testing was then performed to determine a relationship between peak RVOT gradients and the other parameters found to be significantly associated with primary outcome metrics on univariable analysis. These are outlined below in Table 3.
The authors also looked at an association between RVOT gradient and pulmonary valve replacement (PVR). This analysis was conducted in 292 of the 296 eligible patients. Pulmonary valve replacement was performed in 119 (41%) of the patients at a median of 3 years (0.1-12.3 yrs) after CMR evaluation. Using univariable Cox regression analysis, higher RVOT gradients were associated with a need for PVR. Other significant factors include type of palliation (valve sparing vs transannular patch), NYHA class > 1, increased RV volumes and mass, severity of PR and lower RVEF and LVEF. The authors further assessed the effects of mild (< 15 mmHg), moderate (15-30 mmHg) and severe (> 30 mmHg) RVOT gradients and degrees of PR (< 25% and > 25%) on the need for PVR. Patients with < 25% PR and RVOT gradients < 30 mmHg had the lowest risk for PVR (Figure 4 below).
Overall, this is an interesting study that looks at the effect of peak gradient and pulmonary regurgitation on endpoints of death, non-sustained VT and sustained VT as well as need for pulmonary valve replacement and provides some insight into risk factors. However, there was no longitudinal and long term follow up from the surgical procedure with regard to these variables.