Ghelani SJ, Lu M, Sleeper LA, Prakash A, Castellanos DA, Clair NS, Powell AJ, Rathod RH. J Cardiovasc Magn Reson. 2022 Nov 14;24(1):56. doi: 10.1186/s12968-022-00884-y.PMID: 36372887
Take home points:
- Over time, ventricular size increases and function and muscle mass decrease in patients with Fontan circulation as seen on CMR
- Rapid increase in EDVI > ~ 5 ml/BSA^1.3/year may have a higher risk of adverse outcomes (death or need for heart transplant)
Commentary from Dr. Jared Hershenson (Greater Washington DC), section editor of Pediatric Cardiology Journal Watch:
Long-term risk stratification in Fontan patients is necessary to identify patients at higher risk of morbidity and late mortality. Routine cardiac MRI (CMR) every 2-3 years is currently recommended, with prior studies showing that increased ventricular dilation, decreased function, and presence of LGE are risk factors for adverse outcomes. This study was designed to assess changes of ventricular size and function over time to help determine if rate of change may be associated with death or need for heart transplant.
This was a single center retrospective analysis of 156 Fontan patients who had at least 2 CMR exams without any catheter or surgical cardiac interventions between the first and last CMR. The authors describe the CMR protocol in the methods section. The median number of CMRs per patient was 3 over a median follow-up time of 10 years. EDVi and ESVi significantly increased, with an annual increase of EDVi by about 1.63 ml/BSA^1.3. Mass index, EF, and mass to volume ratio significantly decreased, with an annual decrease in mass index of 1.7 g/BSA^1.3 and EF by 0.4%/year. See Table 1. 22 patients met the composite outcome of death or transplant and those patients. These patients had a higher initial EDVi and lower mass index and EF on CMR. When assessing for annualized change, they also had higher significant increases in EDVi and ESVi and decreases in mass index, mass to volume ratio, and EF. A mixed regression model showed that only EDVi (4.7 ml/BSA^1.3/year vs. 0.8 ml/BSA^1.3/year), ESVi, and mass to volume ratio were associated with the composite outcome. See Table 3. More patients with a single right ventricle experienced the composite outcome (21% vs. 8%). The estimated annual rate of change was significantly higher for ESVi and lower in EF for the RV dominant group (Table 5).
The authors discuss the various factors that may contribute to ventricular dilation and why RV dominance may be disadvantageous. Limitations included limited generalizability (patients that had interventions or with pacemakers and ICDs were excluded). They also assumed a linear pattern of change; there may be more sudden and larger changes that could be present if there were more interim CMR studies to compare. Since larger changes were associated with worse outcomes, closer follow-up and surveillance in those patients should be considered.