Patients born with a systemic right ventricle — a right ventricle pressed into service as the heart’s main pumping chamber — do not all deteriorate in the same way. A long-term retrospective study from a large referral cardiac center in Thailand, published in Cardiology and Therapy, followed 207 patients diagnosed between 1975 and 2023 and found that three distinct anatomical subtypes carry three distinct clinical trajectories: one marked by the highest overall burden of ventricular dysfunction, one by the earliest onset of failure, and one by the greatest need for tricuspid valve surgery.

The three conditions share a common physiology. In congenitally corrected transposition of the great arteries (ccTGA), the ventricles and great arteries are mismatched in a way that leaves the morphological right ventricle pumping blood to the body. In patients with transposition of the great arteries who underwent an atrial switch procedure — the Senning operation introduced in 1957 or the Mustard operation using synthetic baffles — the repair produces what the authors call atrial-corrected TGA (acTGA), again leaving the right ventricle systemic. And in right-ventricular-dominant univentricular heart (UVH), a single functioning ventricle of right ventricular morphology, palliated with a Fontan circulation, sustains the systemic circulation. Because the right ventricle is not structurally built for systemic pressures, which are roughly sixfold higher than pulmonary pressures, progressive dysfunction and eventual heart failure are common in all three groups.

What remained unclear, the researchers argue, is whether the timing and pattern of deterioration differ by anatomy. To find out, they assembled a single-center retrospective cohort of 257 patients with a systemic right ventricle aged 2 to 78 years, excluding univentricular patients who never completed Fontan palliation and ccTGA patients who had undergone anatomical repair, leaving 207 eligible for analysis: 53 with acTGA, 75 with UVH after Fontan completion, and 79 with ccTGA. Time zero for the survival analyses was the date of birth, and the primary endpoint was systemic right ventricular dysfunction (sRVd), with progressive moderate-to-severe tricuspid regurgitation and death as secondary endpoints.

Because the study spanned nearly five decades, echocardiographic assessment posed a challenge. Contemporary quantitative tools such as strain imaging and three-dimensional echocardiography were not routinely available, particularly for studies performed between 1979 and the early 2000s, so dysfunction and regurgitation severity were initially graded qualitatively by experienced pediatric cardiologists. The team then re-reviewed all available images: wherever image quality permitted, they measured fractional area change (FAC), using an FAC below 33 percent to confirm systolic dysfunction, and one cardiologist independently re-verified tricuspid regurgitation severity. Every patient previously documented as having dysfunction who had measurable images showed an FAC below 33 percent, supporting the original classification.

The headline result is that systemic right ventricular dysfunction eventually affected one-third of the cohort — 33.3 percent — at a median age of 26.9 years. But the distribution across subtypes was strikingly uneven. Dysfunction was most prevalent in the acTGA group, affecting 20 of 53 patients (37.7 percent), compared with 12 of 75 (16 percent) in the UVH group and 13 of 79 (16.5 percent) in the ccTGA group. The median ages at which dysfunction appeared told a different story: 20.1 years in UVH, 24.8 years in acTGA, and 28.4 years in ccTGA. Freedom from dysfunction at 20 and 40 years was 65.9 percent and 13 percent in acTGA, 30.5 percent and 5.8 percent in UVH, and 43.5 percent and 26.6 percent in ccTGA — differences that were highly significant. In other words, the univentricular group deteriorated earliest and fastest, the atrial-switch group accumulated the largest overall burden, and the congenitally corrected group stayed compensated longest.

Survival followed a related but distinct pattern. At 20 and 40 years, survival was 62.3 percent and 14.7 percent in acTGA, 35.2 percent and 1.5 percent in UVH, and 46.8 percent and 22.7 percent in ccTGA. Twenty patients — 9.7 percent of the cohort — died at a median age of 17.4 years, from causes including arrhythmia, intracranial hemorrhage, and massive bleeding from collateral vessels; eight of the twenty had previously been diagnosed with ventricular dysfunction. Multivariable Cox regression identified pulmonary atresia and New York Heart Association functional class III–IV as independently associated with mortality. Despite the marked differences in trajectories, the biventricular groups — acTGA and ccTGA — held a clear survival advantage over single-ventricle physiology, and overall survival remained broadly comparable between the two biventricular groups.

The predictors of ventricular failure themselves mapped onto anatomy. Pulmonary atresia, an Ebsteinoid tricuspid valve, acTGA, and UVH were all independently associated with sRVd. Across the entire cohort, dysfunction was also significantly linked with concomitant left ventricular dysfunction, defined as an ejection fraction below 55 percent. In a subgroup analysis restricted to patients older than 25, left ventricular dysfunction was independently associated with a five-fold higher likelihood of right ventricular dysfunction, while the presence of right ventricular dysfunction in turn carried a 2.8-fold higher likelihood of left ventricular dysfunction — a bidirectional statistical association the authors interpret as evidence of ventricular interdependence between the systemic right ventricle and the subpulmonary left ventricle. Because the study was retrospective and did not establish the temporal sequence, they caution these should be read as associations, not proof of causality.

Tricuspid regurgitation added a third axis of divergence. Moderate-to-severe regurgitation occurred in roughly one-third of patients and did not differ significantly across the three groups, yet the need for intervention did: tricuspid valve intervention was most frequent in ccTGA, at 13.9 percent, a difference that reached statistical significance, and acTGA patients required intervention at the youngest age. Ventricular septal defect was independently associated with regurgitation in multivariable analysis. Valve morphology mattered too: among patients with an Ebsteinoid valve, two-thirds had significant regurgitation, an excess driven largely by the ccTGA subgroup, although no hazard relationship between valve morphology and regurgitation emerged in the full cohort. The authors suggest that in ccTGA, intrinsic tricuspid valve abnormalities and ventricular dysfunction may create a vicious cycle that progressively worsens hemodynamics.

Arrhythmia burden also split along anatomical lines. Atrial arrhythmias were most common in acTGA, affecting 12 of 53 patients (22.6 percent), though they were not linked to dysfunction, regurgitation, or death. Complete atrioventricular block developed in 17.7 percent of ccTGA patients, consistent with the condition’s recognized natural history, and nearly all of them — 13 of 14 — required pacemaker implantation at a median age of about 21 years. Prolonged QRS duration emerged as a prognostic marker: values above 110 milliseconds were associated with dysfunction and regurgitation, while values above 120 milliseconds correlated with all major adverse endpoints. Non-sustained ventricular tachycardia, by contrast, showed no such correlations.

The authors are careful about what their data can and cannot show. Age distribution, follow-up duration, and treatment era differed across the subgroups, and age-stratified analyses — using cutoffs of 20, 25, and 30 years — showed that among younger patients, mortality was more frequent in ccTGA while dysfunction was more frequent in acTGA, whereas among patients aged 30 or older no significant between-group differences remained in any endpoint. This suggests the higher observed burden of dysfunction in acTGA is at least partly shaped by age and follow-up differences rather than diagnosis alone. Other limitations include the retrospective design’s susceptibility to selection and information bias, reliance on qualitative echocardiographic assessment for some patients, and small event numbers within subgroups. The clinical message, however, stands: these are distinct phenotypes requiring anatomy-specific surveillance, with timely functional assessment tailored to each subtype’s characteristic timeline of deterioration.

Subject of Research: Long-term outcomes of systemic right ventricular dysfunction, tricuspid regurgitation, and mortality across congenital heart disease subtypes

Article Title: Adverse Remodeling and Prognostic Significance of the Systemic Right Ventricle Across Congenital Heart Disease Subtypes

Article References: Puthikitakawiwong, K., Vijarnsorn, C., Tocharoenchok, T., Soongswang, J., Chanthong, P., Chungsomprasong, P., Pacharapakornpong, T., Thammasate, P., Srivichean, A., Durongpisitkul, K., Tantiwongkosri, K., Nitiyarom, E., & Subtaweesin, T. (2026). Adverse Remodeling and Prognostic Significance of the Systemic Right Ventricle Across Congenital Heart Disease Subtypes. Cardiology and Therapy. https://doi.org/10.1007/s40119-026-00477-1

Image Credits: AI Generated

DOI: 10.1007/s40119-026-00477-1

Keywords: systemic right ventricle, congenital heart disease, ccTGA, atrial switch, Fontan, tricuspid regurgitation, ventricular dysfunction, retrospective cohort, survival analysis, echocardiography, heart failure, arrhythmia