A splice-altering synonymous LMNA variant in left ventricular non-compaction associated with progressive conduction disease, ventricular ectopy and systolic decline over 13 years – a case report
Daniela Husser, Alexander Schreiner, Cosima Jahnke, Anne Nitsche, Kerstin BodeAbstract
Background
Lamin A/C (LMNA) cardiomyopathy often presents with early arrhythmias and conduction disease and may express a left-ventricular non-compaction (LVNC) phenotype. Synonymous LMNA variants can be pathogenic when they alter splicing.
Case summary
Thirteen years ago, a 41-year-old woman presented with recurrent atrial fibrillation (AF) and underwent successful catheter ablation. Initial ECG showed first-degree atrioventricular block (PR 350–380 ms) with frequent premature ventricular complexes; echocardiography demonstrated normal chamber size and LVEF 55%. During follow-up, cardiac MRI confirmed LVNC (Petersen NC/C > 2.3). Genetic testing identified LMNA c.1146C>T (p.Gly382=), a splice-altering synonymous variant that activates a cryptic donor at the 3′ end of exon 6, deleting 13 nucleotides and causing a frameshift with a premature stop, consistent with loss-of-function. An ICD was implanted for primary prevention based on the LMNA-risk ventricular tachyarrhythmia calculation. The subsequent course included progressive conduction disease (PR to 550 ms with intermittent second-degree block), high ventricular ectopy with non-sustained VT, and LVEF decline to 30-35%. Later, AF and atypical atrial tachycardia recurred and were managed with device reprogramming and medical therapy. Due to widening QRS (≈140 ms) and high right ventricular pacing burden, the system was upgraded to CRT-D. Ongoing management focuses on rhythm control and guideline-directed heart-failure therapy.
Discussion
This case illustrates arrhythmia-led cardiolaminopathy with LVNC morphology and systolic decline associated with a splice-altering synonymous LMNA variant. Gene-specific risk features (variant type, atrioventricular block, non-sustained VT) supported early device therapy beyond EF-only thresholds. Integration of genotype, imaging, and arrhythmic/conduction findings enabled timely, gene-informed care over long-term follow-up.