Prolonged left ventricular twist in cardiomyopathies: a potential link between systolic and diastolic dysfunction

Abstract

AIMS: Left ventricular (LV) twist and untwist play a major role in LV mechanics. We sought to acquire new pathophysiological insights in cardiomyopathies (CM) studying LV twist dynamics by speckle tracking imaging (STI). METHODS AND RESULTS: Standard echo-Doppler and STI study were performed in 67 CM patients divided in four age- and sex-matched subgroups: 18 with apical hypertrophic cardiomyopathy (Group A); 20 with asymmetrical hypertrophic cardiomyopathy (Group B); 15 with dilated cardiomyopathy (Group C); 14 with LV non-compaction (Group D). As controls, 34 age- and sex-matched normal subjects were studied. Compared with control group, all CM Groups showed significantly lower longitudinal, circumferential, and radial myocardial deformations (P < 0.05). LV twist was correlated with ejection fraction (EF; r = 0.62; P < 0.0001). Furthermore, all CM patients had a significantly lower twist rate (P < 0.05) and delayed onset of untwist (P < 0.01). Of interest a significant correlation was found between isovolumic relaxation time and untwist onset (r= 0.485, P < 0.0001). In addition, a significant correlation was found between longitudinal deformations and the onset of untwist (strain: r = 0.46, P = 0.0001; strain rate: r = 0.33, P = 0.0056) and between longitudinal strain rate and twisting rate (r= -0.38; P = 0.0015). CONCLUSION: (i) All CM patients show an impairment of longitudinal, circumferential, and radial myocardial deformations; (ii) LV peak twist is impaired only in CM with reduced EF but preserved in those with normal or increased EF; (iii) LV twist is prolonged and untwisting onset is delayed in all CM, suggesting that a mechanical adaptation to subclinical systolic abnormalities might induce, by a prolonged LV twist, the early onset of diastolic dysfunction.