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Spot the difference: LV trabeculation vs. LV noncompaction
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The number of publications related to left ventricular noncompaction in recent years has risen sharply. However, there are still many unknowns regarding its etiology and pathology, but also the diagnosis, prognosis and management of patients affected by this condition.
Prominent myocardial trabeculations and deep intertrabecular recesses are most likely a result of an early arrest of the compaction process during embryogenesis and are thus morphological features of left ventricular noncompaction (LVNC).
LVNC is thought to be rare. The prevalence in unselected patients referred for an echocardiogram in a tertiary center ranges from 0.014% to 1.26%, and in patients with HF ranges from 3% to 4%. There is a genetic link in up to 50% of cases in which patients have close relatives with cardiomyopathy. Genetic confirmation or exclusion of LVNC is currently challenging, as often known disease-related mutation cannot be identified and absence of known mutations does not exclude LVNC.
As shown by Oechslin and colleagues in the Journal of the American College of Cardiology in 2000, clinical presentation and sequelae of LVNC range from a lack of symptoms to severe systolic dysfunction with HF, arrhythmias, thromboembolic events and sudden cardiac death.
Multiple imaging approaches
Filip Zemrak
Steffen E. Petersen
Currently, there are multiple echocardiographic and cardiac magnetic resonance (CMR) approaches to measure the extent of LV trabeculations. CMR criteria differ based on selected imaging planes — short vs. long axis planes — with regard to the selected phase of the cardiac cycle (diastole vs. systole) and how the extent of LV trabeculation was measured (eg, ratio of thickness of trabeculated and compacted myocardial layers vs. percentage of trabecular to total LV mass). Importantly, all of the imaging criteria take into account only the appearance of the myocardium without considering the pre-test probability for LVNC.
Interpreting the test with clinical information is especially important in this particular condition. More than 25% of the population-representative individuals without cardiac disease or symptoms could fulfill imaging criteria for LVNC, as we have recently shown in the Multi-Ethnic Study of Atherosclerosis.
Diagnosis, management, treatment
The diagnosis of LVNC should only be considered in patients with pre-test probability higher than in the general population, such as those investigated for LVNC-related symptoms; patients with documented impaired systolic function or coexistent neuro-muscular disorder; and patients with a family history of cardiomyopathy.
Appreciating the difference between affected patients with excessive trabeculation and LV systolic dysfunction and individuals who may meet the imaging criteria for LVNC but, have normal LV function and otherwise low pre-test probability for LVNC, is essential for clinical management.
In patients with a clear-cut diagnosis of LVNC with impaired LV systolic function, treatment should follow current HF guidelines, such as the 2013 recommendations from the American College of Cardiology Foundation and American Heart Association, which contain specific consideration of ACE inhibitors, beta-blockers, cardiac resynchronization therapy and implantable cardioverter defibrillators.
Image provided by: Filip Zemrak, MD, and Steffen E. Petersen, MD, DPhil, MPH, FESC
Additionally, patients with LVNC with and without atrial fibrillation are at higher risk for thromboembolic complications. Patients with LVNC and AF should receive anticoagulation according to standard guidelines (if CHA2DS2-VASc score ≥1). Anticoagulation should also be considered when standard criteria for the intervention are not met, especially in patients with ejection fraction <40%. Recently published data by Ashrith and colleagues in the Journal of Cardiovascular Magnetic Resonance demonstrated that patients with incident HF and cardiomyopathy with a higher burden of LV trabeculation had a smaller improvement in LV function after initiation of therapy and remained more symptomatic compared with similar patients with less LV trabeculation.
However, treatment of patients with LVNC has not been established in large cohort studies or clinical trials, and any recommendations need to be justified and considered on an individual basis.
In the much more common clinical scenario, where we find excessive trabeculation in a patient with no suspicion for LVNC (low pre-test probability), we should avoid “labeling” the patient with a diagnosis of LVNC.
We have recently shown that in relatively healthy individuals in the community, those with greater trabeculation had minor relative changes in LV volumes compared with those with lesser trabeculation, but these changes were unlikely to have clinical implications. Our study did not find a clinically relevant impact of trabeculae on LV function during a 10-year period in a population of representative asymptomatic adults. This suggests that in people with marked LV trabeculation, but low pre-test probability for LVNC, that there is no clear need for follow-up imaging or pharmacotherapy.
Individuals with high suspicion for LVNC cardiomyopathy in view of symptoms or positive family history who have preserved systolic function should remain under close follow-up, especially with cardiac imaging. In our practice, we also recommend family screening of first-degree relatives.
Use of clinical and cardiac imaging information
In summary, a high degree of LV trabeculation is a common finding on cardiac imaging and in most cases does not implicate cardiomyopathy. Diagnostic labeling of LVNC and proposing management strategies should be made using both clinical and cardiac imaging information.
Disclosure: Zemrak and Petersen report no relevant financial disclosures.