Spiral Septal Morphology Distinguishes Arrhythmic from Idiopathic DCM and Links to Prognosis

BACKGROUNDDilated cardiomyopathy (DCM) presents a highly heterogeneous spectrum, including a familial subset with elevated arrhythmic risk. Traditional demographic and imaging markers, such as late gadolinium enhancement, have been inadequate for identifying high-risk patients before arrhythmic events. Remodelling of the interventricular septum--central to ventricular mechanics and conduction--may offer improved risk stratification. OBJECTIVESTo identify differences in left ventricular (LV) morphology between arrhythmic and idiopathic dilated cardiomyopathy (aDCM vs iDCM), and to identify LV remodeling patterns that link to adverse outcomes. METHODSThree-dimensional LV shape models were constructed from end diastolic cardiovascular magnetic resonance images of 102 individuals subdivided by their idiopathic or arrhythmic subgroup allocation. A statistical shape model was built using principal component analysis. A linear discriminant analysis determined shape features of the arrhythmic subgroup and increased composite arrhythmic outcome of sudden cardiac death, aborted sudden cardiac death, and sustained ventricular tachycardia. RESULTSThe idiopathic DCM group displayed larger mass, length, diameter, mass to volume ratio, and a mild spiral pattern of thicker septal walls (p=0.004). The arrhythmic DCM group displayed a more conical (wider basal and mid wall to apical diameter) LV, and the lack of the spiral septal morphology was the most significant feature (p=0.006) to identify subjects that had the composite arrhythmic outcome. CONCLUSIONThe LV morphology derived suggests a differentiation of arrhythmic DCM patients beyond size, function and LGE presence. This was distinctive and captured shape features that suggest alternate mechanisms for arrhythmic risk linked to a pattern of remodeling. Graphical AbstractAssessing LV morphology signature of arrhythmic DCM phenotype O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/26346514v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1f47f7aorg.highwire.dtl.DTLVardef@dd5d08org.highwire.dtl.DTLVardef@106ef07org.highwire.dtl.DTLVardef@36eb76_HPS_FORMAT_FIGEXP M_FIG C_FIG