Left ventricular hypertrabeculation

Article written and reviewed by Dr Luca Moretti

Left ventricular hypertrabeculation is an anatomic phenotype in which trabeculae of the endocardial surface appear numerous or prominent and delimit recesses communicating with the cavity. The finding may accompany a cardiomyopathy, but it also occurs in healthy hearts and during hemodynamic adaptations. Correct definition therefore requires separating trabecular morphology from the diagnosis of disease.

The availability of high-resolution echocardiography and cardiac magnetic resonance has enormously increased the ability to visualize the apex and lateral wall. In parallel, the number of people exceeding thresholds developed in small cohorts with overt disease has increased, despite the absence of symptoms, dysfunction or family history. The contemporary problem is not recognizing trabeculae, but establishing when they have clinical significance. Pretest probability conditions the value of every geometric ratio.

The term noncompaction presupposed that the embryonic trabeculated layer should compact and that disease resulted from arrest of this process. Data on cardiac development do not support such a simple transformation of the noncompacted layer into compact myocardium. For this reason, recent documents prefer to describe excessive trabeculation or hypertrabeculation and reserve noncompaction cardiomyopathy for truly pathologic contexts. Terminologic neutrality reduces an unproven embryologic inference.

The distinction does not deny that there are patients with marked trabeculation, dysfunction, arrhythmias, emboli and familial disease. Rather, it indicates that risk does not automatically derive from shape and that many genetic cardiomyopathies may share this trait. The diagnostic task is to identify the substrate accompanying the trabeculae. Contextual diagnosis avoids both trivializing disease in a sick patient and pathologizing an innocuous finding.

Trabecular anatomy and ventricular development

Trabeculae are muscular ridges lined by endocardium that increase the complexity of the ventricular inner surface. In the embryonic heart they facilitate exchange and function before full maturation of the coronary circulation and contribute to the architecture of conduction and the ventricular wall. In the adult heart they remain mainly at the apex and in the inferior and lateral regions, with wide individual variability. Anatomic continuity makes an absolute boundary between normal and excessive artificial.

The smoother outer layer is called compact, whereas the inner portion including trabeculae and recesses is described as trabeculated. This two-layer representation is useful for some measurements, but the actual wall has interwoven fibers and three-dimensional transitions. Papillary muscles, false tendons and muscular bands may be included or excluded differently by operators. Two-dimensional simplification explains some of the variability among criteria and modalities.

The historical hypothesis of arrested compaction influenced nomenclature, illustrations and genetic interpretation. Contemporary anatomic studies instead describe differential growth of the layers and formation of compact myocardium without necessary conversion of preexisting trabeculae. Adult morphology therefore cannot by itself reconstruct an embryonic event. Developmental biology invites us not to confuse visual similarity with causal mechanism.

Intertrabecular recesses communicate with the ventricular cavity and fill with blood, whereas coronary sinusoids or fistulas are different structures. Color Doppler can demonstrate flow within the recesses, but perfusion does not establish pathologic status. The apex is also vulnerable to foreshortening and artifacts. Correct acquisition precedes any measurement and prevents creation of a false bilaminar wall.

Nomenclature and phenotypic spectrum

The terms hypertrabeculation, excessive trabeculation and noncompaction have been used as synonyms, but convey different levels of certainty. The first two describe what appears on imaging; the third has been used both for a morphologic criterion and for a clinical cardiomyopathy. This ambiguity makes many studies incomparable. Explicit terminology should indicate technique, criterion and associated abnormalities.

A useful report describes location, extent, global and regional function, volumes, compacted thickness, right ventricle, LGE and any congenital heart disease. Simply stating compatible with noncompaction transfers to the clinician a conclusion not supported by the geometric finding. Even the adjective isolated requires exclusion of dysfunction, arrhythmias, syndromes and family history, not merely other echocardiographic abnormalities. Complete phenotyping makes the report actionable.

The spectrum includes an asymptomatic variant with normal function, a reversible adaptation to preload, a trait associated with congenital heart disease and an element of dilated, hypertrophic or arrhythmogenic cardiomyopathy. In children it may be part of chromosomal, metabolic or neuromuscular syndromes. A single image therefore spans very different mechanisms. Etiologic plurality precludes a uniform prognosis.

Possible involvement of the right ventricle is difficult to define because the right ventricle is physiologically more trabeculated. Criteria derived from the left ventricle cannot be transferred directly. Right ventricular assessment should focus on size, function, wall motion, pressure and signs of a specific cardiomyopathy. Isolated right ventricular trabeculation has even lower specificity.

Method-dependent epidemiology

Prevalence varies by orders of magnitude among clinical registries, echocardiographic screening, CMR cohorts and pediatric populations. A threshold applied at a heart failure center selects different people from the same threshold applied in the general population. The number of measured segments, cardiac phase and image quality also change the result. Methodologic prevalence does not necessarily coincide with that of a biological disease.

In the MESA study, very pronounced trabeculation in adults without heart disease was not associated with clinically relevant adverse remodeling during approximately nine and a half years of follow-up. In clinical CMR cohorts, a substantial proportion exceed the Petersen ratio without an independent increase in events after accounting for other abnormalities. These data do not prove harmlessness in every patient, but reduce the prognostic weight of the isolated measurement. The population context is essential for interpreting risk.

Differences related to ancestry have been observed, with criteria met more often in some Black populations even without heart disease. Body surface area, sex and ventricular volume influence visualization, while reference values are not always adequately stratified. Applying a universal threshold can therefore introduce bias. Demographic variability requires judgment, not unvalidated arbitrary corrections.

Neonates and children represent a distinct context. Apparent prevalence is lower, but the yield for genetic and syndromic conditions may be greater, especially with dysfunction or congenital heart disease. Growth trajectories modify dimensions and ratios, and adult criteria are not always validated. The pediatric perspective prioritizes evolution, genotype and multisystem involvement.

Echocardiography and historical criteria

Echocardiography is the first examination because it assesses trabeculae, function, flow and associated heart disease in real time. Apical views should avoid foreshortening and include the entire apex; echocardiographic contrast can delineate the endocardium when the acoustic window is inadequate. Strain adds longitudinal functional assessment but is not specific for hypertrabeculation. Image quality determines the credibility of the criterion more than the decimal precision of the ratio.

The Chin criteria measure at end-diastole the ratio between the distance from the epicardium to the trough of the recess and the distance from the epicardium to the tip of the trabecula, considering a value of 0.5 or less diagnostic. The Jenni criteria require a two-layered wall with a ratio of noncompacted to compacted component greater than two at end-systole, typical trabeculae, flow within the recesses and, in the original formulation, absence of other structural cardiac abnormalities. The Stöllberger criteria require more than three prominent trabeculae apical to the papillary muscles, with synchronous motion and intertrabecular perfusion. The diversity of criteria produces imperfect agreement in the same patient.

Cardiac phase is crucial because the compacted layer appears thicker in systole and the ratio changes. An end-diastolic measurement cannot be compared with an end-systolic one without specifying this. Choosing the most extreme segment also increases sensitivity and reduces robustness. Consistent metrology requires documented protocol, plane and phase.

In patients with systolic dysfunction, historical echocardiographic criteria identify a surprisingly high percentage and may also be met by controls. Cavity dilation and better separation of trabeculae can accentuate the finding. Dysfunction does not prove that trabeculae caused it, nor does it make them irrelevant. The temporal relationship between remodeling and trabeculation often remains indeterminate.

The report should avoid adding incompatible criteria as though they were independent votes. Meeting multiple thresholds derived from the same image is not equivalent to having more etiologic evidence. It is instead useful to compare previous studies, verify function, look for LGE with CMR and integrate ECG and family history. Multimodal convergence is more valuable than multiplying morphologic ratios.

Cardiac magnetic resonance

CMR visualizes the entire ventricle with high blood-myocardium contrast and reduces the limitations of echocardiographic apex imaging. It measures volumes, mass, function, fibrosis and, with mapping, diffuse tissue abnormalities. Its greater sensitivity, however, makes incidental trabeculation even more frequent. Anatomic superiority does not automatically guarantee greater clinical specificity.

The Petersen criterion uses a ratio of trabeculated to compacted thickness greater than 2.3 at end-diastole, measured on long-axis images and outside the extreme apex. The Jacquier criterion considers a trabeculated mass greater than 20% of global ventricular mass diagnostic. The Grothoff criteria combine an indexed noncompacted mass greater than 15 g/m², a noncompacted fraction greater than 25% of global mass, a noncompacted-to-compacted layer ratio of at least 3 in at least one of segments 1–3 or 7–16, excluding apical segment 17, and at least 2 in basal segments 4–6. The plurality of CMR criteria reflects the absence of an independent biological gold standard.

Contouring trabeculae as part of the cavity or myocardium changes mass, volume and ejection fraction. Papillary muscles and bands are handled differently by software, while compacted thickness near the apex may approach spatial resolution. Selecting the segment with the maximum value favors extreme measurements. Post-processing dependence should be considered when comparing centers and during follow-up.

Fractal analysis quantifies endocardial border complexity and offers a continuous measure less dependent on a single wall. This approach also requires normative values, standardization and demonstration of clinical utility. More sophisticated technology does not by itself resolve the distinction between adaptation and disease. Automated quantification should be validated against outcomes and not only against historical diagnoses.

LGE has greater prognostic relevance than the amount of trabeculation in several studies because it signals scar from an underlying cardiomyopathy. Pattern and location can suggest dilated forms, previous myocarditis, muscular dystrophy or other etiologies without being pathognomonic. T1, T2 and extracellular volume answer different questions. Tissue characterization shifts attention from the endocardial surface to the myocardial substrate.

Physiologic adaptation and loading conditions

During pregnancy, increases in plasma volume and cardiac output modify ventricular size and loading conditions. Longitudinal studies have observed the appearance of previously absent trabeculae in about one quarter of healthy women, with regression in the majority after delivery. The finding demonstrates that trabecular visibility can change in adulthood and is not specific to an embryonic defect. Preload-related reversibility should be considered before making permanent diagnoses.

Pregnancy does not, however, automatically make every finding physiologic. Dysfunction, disproportionate symptoms, family history, arrhythmias or lack of recovery require evaluation for peripartum cardiomyopathy and other diseases. Comparison with prepregnancy and postpartum images is particularly informative. Obstetric timing distinguishes adaptation, heart failure and a preexisting condition.

In endurance athletes, physiologic dilation and increased preload make trabeculae more visible, with a higher prevalence than controls in some cohorts. Most athletes who meet a morphologic criterion do not have the clinical features of cardiomyopathy. Performance, ECG, exercise response, function, LGE and family history define the gray zone. Sports evaluation should not use trabeculation as an isolated reason for disqualification.

Chronic anemia and other high-output states have been associated with prominent trabeculae, probably through loading conditions and geometry. A cavity dilated by another cardiomyopathy can also separate and make preexisting structures more evident. It is not always possible to determine whether trabeculae have increased or are simply better visualized. Volume dependence limits causal interpretations based on two nonstandardized images.

Pathologic associations and genetics

Hypertrabeculation may accompany dilated, hypertrophic and arrhythmogenic cardiomyopathies with variants in sarcomeric, cytoskeletal or membrane genes. MYH7, MYBPC3, TTN and ACTC1 occur in families with overlapping phenotypes, but are not genes specific to trabeculation alone. Genetic diagnosis should therefore follow the primary phenotype and segregation. Genetic pleiotropy explains why relatives with the same variant may have different ventricular phenotypes.

In children, Barth syndrome due to TAZ, mitochondrial diseases, muscular dystrophies and other neuromuscular disorders can include marked trabeculation. Sinus bradycardia and aortic dilation in some families with HCN4 constitute another recognizable association. The finding then becomes one piece of a syndrome, not the final diagnosis. Extracardiac phenotyping increases the yield of molecular testing.

Congenital heart diseases, particularly septal defects, valvular abnormalities or complex malformations, may coexist with hypertrabeculation. Abnormal loading and a shared developmental basis may both contribute. Historical definitions of the isolated form excluded these abnormalities, creating categories that do not reflect the full clinical spectrum. Associated heart disease should be described and treated according to its own physiology.

Genetic testing is reasonable when dysfunction, LGE, significant arrhythmias, congenital heart disease, a syndrome, family history or pediatric onset is present. In an asymptomatic adult with normal function and ECG, the yield of a broad panel is lower and the risk of uncertain variants is substantial. A VUS does not demonstrate pathogenicity and should not be used to diagnose relatives. Genetic selection protects against false precision.

Manifestations and differential diagnosis

Isolated hypertrabeculation produces no specific symptoms. Dyspnea, pain, palpitations, syncope or embolism require identification of function, rhythm, thrombi and alternative diseases. Attributing the symptom to trabeculae before this assessment may delay coronary, inflammatory, valvular or pulmonary diagnoses. Symptom causality must be demonstrated through the associated substrate.

Dilated cardiomyopathy may present with prominent trabeculae due to remodeling and shares numerous genes. Myocarditis and sarcoidosis produce dysfunction and LGE with incidental trabeculation, whereas apical hypertrophy can simulate a thin compacted layer. Endomyocardial fibrosis, apical thrombi and prominent papillary muscles further complicate the image. Tissue differential diagnosis requires cine imaging, contrast and distribution of abnormalities.

An apical thrombus can lie between trabeculae and be difficult to distinguish from myocardium. Echocardiographic contrast and CMR with appropriate sequences clarify vascularization and tissue characteristics. The presence of recesses alone does not demonstrate sufficient stasis to form thrombi. Thrombus assessment is guided by dysfunction, previous embolism and image quality.

The ECG may be normal with an isolated finding. Conduction blocks, pathologic repolarization, pre-excitation or arrhythmias instead increase the probability of genetic, neuromuscular or structural disease and require a specific pathway. Holter monitoring is not prescribed indefinitely for morphology alone, but is useful with palpitations, syncope, dysfunction or family history. Electrical coherence completes the anatomic interpretation.

Clinical pathway and stratification

The first step verifies that the finding is real using non-foreshortened images, multiple planes and, if necessary, contrast or CMR. The second defines function, volumes, LGE, ECG and symptoms; the third examines family history, congenital heart disease and extracardiac manifestations. Only then is it decided whether the picture is physiologic, indeterminate or cardiomyopathic. Phenotypic sequence prevents the measurement from retrospectively conditioning the entire history.

A three-generation pedigree includes heart failure, transplantation, ICD implantation, sudden death, early stroke, congenital heart disease and neuromuscular diseases. Generic reports such as enlarged heart should be verified when possible. Absence of family history does not exclude a de novo variant or incomplete penetrance. Documented family history carries more weight than vague similarities.

In indeterminate cases, reasonable follow-up assesses stability of function and symptoms without automatically creating lifelong surveillance. Interval and modality depend on age, degree of uncertainty and borderline findings. Regression after pregnancy or correction of loading conditions supports adaptation, but isolated persistence does not prove disease. Longitudinal observation is a diagnostic tool when it leads to a defined decision.

In children, growth, development, CK, neurologic examination, perinatal history and metabolic assessment according to clues are added. Normal function today does not guarantee a benign course in every syndrome, while excessive monitoring can burden the family. The plan is built on the etiologic suspicion rather than a universal frequency. Pediatric surveillance is more cautious but remains proportionate.

Treatment and physical activity

There is no therapy that should reduce trabeculae, and their amount has not been shown to be a therapeutic target. If function and rhythm are normal, medications are not prescribed for the finding alone. When cardiomyopathy is present, treatment follows heart failure, gene, arrhythmias and causal disease. The therapeutic target is the pathologic process, not the endocardial appearance.

Anticoagulation is not recommended for isolated trabeculation. Atrial fibrillation, ventricular thrombus, previous embolism and other indications are managed according to clinical risk, considering function and bleeding. The theory of universal stasis within the recesses does not replace outcome data. Thromboembolic prevention must avoid both undertreatment of real risk and unjustified exposure.

Pacemakers and ICDs respond to conduction disorders, documented arrhythmias, function and risk of the underlying cardiomyopathy. No NC/C ratio alone constitutes an indication. Electrophysiologic testing is likewise reserved for specific clinical questions. Device therapy should not turn an imaging classification into an arrhythmic category.

Physical activity is permitted with an isolated finding and normal evaluation, according to capacity and general preventive guidance. If dysfunction, arrhythmias, LGE or a high-risk variant coexist, exercise prescription and competitive sport follow the specific cardiomyopathy. Deconditioning can harm health and well-being without reducing trabeculae. Sports-related decision-making integrates objective risk and the person's goals.

Pregnancy, family and prognosis

Isolated trabeculation does not contraindicate pregnancy or automatically require a high-risk pathway. Preconception assessment becomes necessary with dysfunction, arrhythmias, previous heart failure, genetic cardiomyopathy or family history. During follow-up, volume and function matter more than the visual increase in trabeculae. Maternal risk stratification distinguishes physiologic adaptation from reduced myocardial reserve.

Screening of relatives is indicated when the proband has cardiomyopathy, a pathogenic variant or a coherent familial cluster. It is not proportionate to subject a healthy family indefinitely to imaging for an isolated adult finding. If a causal variant is identified, targeted testing clarifies who requires surveillance. Family cascade screening should begin from a robust diagnosis.

In adults, the degree of trabeculation has not shown consistent independent prognostic value when function, dilation and LGE are taken into account. Events observed in historical cohorts largely reflect selected patients with advanced cardiomyopathy. This does not eliminate risk in the affected subgroup, but attributes it to the correct determinants. Phenotype-guided prognosis is more accurate than prognosis based on morphology alone.

An incidental report should conclude with the degree of certainty and the elements that modify significance, rather than an automatic definitive label. Explaining that an anatomic variant may require verification without being a disease reduces anxiety and the cascade of testing. Conversely, dysfunction, LGE or family history should be communicated clearly and followed. Clinical proportionality is the most important outcome of a modern diagnosis of hypertrabeculation.

Reassessment of the diagnosis remains appropriate when new symptoms, family events or techniques capable of better characterizing tissue emerge. This does not mean periodically repeating every examination, but reopening the question only when new information can modify prognosis, treatment or counseling. An updateable diagnosis preserves rigor without turning initial uncertainty into indefinite surveillance.