Overall perioperative mortality in pediatric cardiac surgery is currently approximately 2%-3%, although it remains higher for complex procedures. This improvement has shifted attention toward other components of surgical outcomes, including residual lesions, which are associated with a more difficult recovery, further interventions, and worse long-term outcomes.
The American Heart Association (AHA) scientific statement led by Costello et al. reviews the evidence on important residual lesions and early unplanned cardiac reinterventions after pediatric cardiac surgery. It addresses their prevention, diagnosis, and treatment, together with communication with families and opportunities for quality improvement. The document combines observational studies, validation of prognostic tools, and practical expert considerations, with decisions individualized according to anatomy, physiology, and available resources.
Early unplanned reinterventions (surgical, catheter-based, or both during the index hospitalization) occur in approximately 5% of pediatric cardiac operations and are more frequent in neonates. They are related to, but distinct from, major residual lesions: in the study cited by the authors, these were identified in 15% of aortic arch/ventricular septal defect repairs and 35% of complete atrioventricular septal defect repairs.
The need for reintervention is associated with an almost 7-fold higher adjusted risk of in-hospital mortality; approximately 1 in 6 patients undergoing reintervention dies during the same hospitalization. Important residual lesions are also associated with greater resource utilization and worse outcomes after hospital discharge.
COMMENTARY:
Samuel Gorovitz and Alasdair MacIntyre’s reflections on the fallibility of medicine provide a useful perspective from which to read this statement. In pediatric cardiac surgery, anatomical and physiological complexity limits our ability to anticipate and control every outcome. The challenge is to recognize these limits without attributing to them what we can still improve. Residual lesions place the team precisely at this boundary: determining which defect can be accepted, which requires correction, and when the patient’s course should prompt reconsideration of the initial decision.
The prognostic associations summarized in the document demonstrate the importance of the problem, but they do not allow us to attribute excess mortality to the reintervention itself or to assume that every episode could have been prevented through better technical execution. Patient severity, anatomical complexity, and the circumstances leading to reintervention influence both the decision and the outcome.
Quality begins before entering the operating room
The technical imperative described in the statement expresses the aspiration to leave the operating room with the best possible anatomical result. Its scope begins before the repair itself: an incomplete diagnosis or a strategy that fails to adequately anticipate postoperative physiology may compromise the outcome even when the surgical procedure is technically well executed.
In complex congenital heart disease, planning requires an understanding of the circulation we aim to achieve and the conditions required for it to function. Multidisciplinary review of the anatomy should help establish the strategy and anticipate potential difficulties during recovery. Thus, the assessment of a residual lesion encompasses both the defect itself and its significance within the resulting circulation.
The occurrence of residual lesions should prompt a review of this entire process. Automatically equating them with technical error would prevent us from identifying potentially modifiable problems in diagnosis, planning, or follow-up.
Going back on CPB: a decision that requires more than a gradient
Assessment after separation from cardiopulmonary bypass (CPB) is a critical moment. Transesophageal or epicardial echocardiography allows evaluation of the repair and, in selected cases, can be complemented by direct pressure measurements, oxygen saturations, or intraoperative angiography.
The Residual Lesion Score (RLS), developed from the Technical Performance Score (TPS), provides a systematic framework for classifying the result: class 1, no or trivial residual lesions; class 2, minor residual lesions; and class 3, major residual lesions. In addition to its prognostic value, it provides a common language for communicating and reviewing findings.
In general, the statement favors intraoperative correction of major residual lesions when the anatomy allows the repair to be improved. The decision requires balancing the hemodynamic consequences of the lesion, the likelihood of achieving a better result, and the morbidity associated with another CPB run, with or without an additional period of cardioplegic arrest.
The thresholds included in the algorithm—such as a mean atrioventricular valve gradient >6 mmHg, at least moderate aortic or atrioventricular valve regurgitation, or an outflow tract gradient >40 mmHg—help guide this assessment. Their interpretation requires an understanding of the mechanism of the lesion, loading conditions, and the potential for further repair.
Class 2 lesions also deserve attention. Minor residual lesions are generally well tolerated but may become important in palliated or particularly vulnerable circulations. Anatomical grading helps structure the assessment; the decision ultimately depends on how the defect affects the individual patient and what improvement another intervention might realistically achieve.
Accepting a residual lesion requires a plan
Intraoperative assessment takes place under loading and support conditions that will change during recovery. The statement reports agreement between intraoperative and discharge echocardiographic assessment in approximately two-thirds of procedures; in the remaining cases, the severity of minor residual lesions may change.
Therefore, the decision to accept a residual lesion must carry over into the handoff from the operating room to intensive care. Known defects, how they were assessed, their expected impact, and the findings that should trigger reassessment should all be explicitly communicated. This information allows the patient’s course to be interpreted against a shared expectation.
Severe, prolonged, or unexpected low cardiac output and unexplained difficulty weaning from mechanical ventilation should trigger a search for important residual lesions. The assessment must also remain open to other causes of an unfavorable course: myocardial dysfunction and an anatomical lesion may coexist.
In patients requiring postoperative ECMO, the search for residual lesions should be systematic. The cohorts cited in the statement identified lesions considered amenable to reintervention to facilitate weaning from support in 28% of a general pediatric population and 83% of a neonatal population. These findings justify a high level of diagnostic suspicion and formal consideration of cardiac catheterization according to the findings and clinical situation.
Timely reintervention requires defining what we expect from waiting
In the cited study of neonates undergoing reintervention after a Norwood operation, every 5-day increase in time to reintervention was associated with a 20% increase in the adjusted odds of death or transplantation. Its observational nature prevents interpreting this finding as a causal effect of delay, but it reinforces concerns about allowing an unfavorable hemodynamic state to persist. costello-et-al-2026-important-r…
Observation needs predefined goals: what improvement is expected, which data will be used to assess it, and which findings will trigger a change in strategy. A lesion initially considered acceptable may require a different decision if support requirements increase, organ dysfunction develops, or recovery deviates from the expected course.
When reintervention is considered, the choice between surgery and catheterization depends on the location and mechanism of the lesion, its accessibility, and the result that each procedure can offer. Cardiac catheterization may also answer important diagnostic questions when noninvasive imaging is insufficient.
The data on early catheterization require a complete reading. In a multicenter cohort of 1399 postoperative catheterizations, there were no procedure-related deaths; however, high-severity adverse events occurred in 8.9% and life-threatening adverse events in 2.4%. These findings support its use in selected patients, with multidisciplinary planning and the ability to respond to complications. The observed safety does not, by itself, demonstrate that broader use improves outcomes.
Reviewing decisions and explaining uncertainty
Variability between centers provides an opportunity to review criteria and learn from different practices. An isolated reintervention rate, however, provides an incomplete measure of quality of care. It must be interpreted alongside patient complexity, detected residual lesions, and subsequent outcomes. Reducing the frequency of reinterventions only makes sense if it is accompanied by better repairs and better outcomes.
For our centers, one practical application would be to incorporate intraoperative and discharge RLS into morbidity and mortality conferences, strengthen structured handoffs with intensive care teams, and establish agreed criteria for reassessment. Each case review should reconstruct what was known, which options were feasible, and what prompted the decision. Knowing the outcome makes it easier to judge a decision retrospectively; learning from it requires reconstructing the circumstances in which it was made.
Communication with families is part of this responsibility. Before surgery, the goals of the procedure and the possibility of residual lesions or additional interventions should be explained. If these occur, the team should communicate in a coordinated manner what is known, what uncertainties remain, and what options are available, avoiding attribution of causes before an adequate assessment has been completed.
The complexity of pediatric cardiac surgery makes it impossible to guarantee a perfect repair in every patient. The challenge is to distinguish the limits we must accept from the opportunities for improvement that remain within our reach. Accepting a residual lesion requires justifying the decision, anticipating its potential consequences, and establishing when it should be reconsidered. Recognizing our fallibility also means being prepared to change course when the patient’s evolution challenges what initially seemed reasonable.
REFERENCE:
Costello JM, Mazwi ML, Riley CM, Gonzalez de Alba CE, Olivieri LJ, Rigsby CK, et al; American Heart Association Congenital Cardiac Defects Committee; Council on Lifelong Congenital Heart Disease and Heart Health in the Young; Council on Clinical Cardiology; and the Council on Cardiovascular and Stroke Nursing. Important Residual Lesions and Early Unplanned Reinterventions After Pediatric Cardiac Surgery: A Scientific Statement From the American Heart Association. Circulation. 2026 Sep 1. doi: 10.1161/CIR.0000000000001465.
