Early detection of left ventricular dysfunction in first-degree relatives of diabetic patients by myocardial deformation imaging: The role of endothelial glycocalyx damage.

BACKGROUND: First-degree relatives of type-2 diabetes patients (FDR) present insulin resistance. We investigated whether FDR and dysglycaemic subjects demonstrate abnormal endothelial glycocalyx and LV deformation during postprandial hyperglycemia.

METHODS: We studied 40 FDR with normal oral glucose test (OGTT), 40 subjects with abnormal OGTT (dysglycaemic) and 20 subjects with normal OGTT without parental history of diabetes (normoglycaemic). At 0 and 120min of OGTT we measured: a) LV longitudinal strain (LS) of subendocardial, mid-myocardial and subepicardial layers, global LS (GLS), peak twisting (pTw), untwisting velocity (pUtwVel), by speckle tracking echocardiography b) perfused boundary region (PBR) of the sublingual arterial microvessels; high PBR values represent reduced glycocalyx thickness. Insulin resistance was evaluated using insulin sensitivity index (ISI).

RESULTS: ISI was related with baseline PBR, GLS and pTw in all subjects (p<0.05). Compared to normoglycaemics, FDR and dysglycaemics had higher PBR, lower ISI, GLS (-18.4±2.6 and -16.8±2.0 vs. -19.2±2.4%), subendocardial LS (-19.0±4.2 and -17.9±3.0 vs. -20.1±3.4%), pTw (14.4±4.4 and 15.6±6.4 vs. 16.9±6.5deg) and pUtwVel (p<0.05 for all comparisons). A GLS<-18% identified FDR with LV dysfunction (p=0.016). Post-OGTT, GLS and the subendocardial LS decreased while pTw and pUtwVel increased in FDR and dysglycaemics (p<0.05) indicating prevalence of the motion of the subepicardial over a dysfunctioning subendocardial myocardial helix. Increased PBR was related with impaired deformation markers at baseline and 120min of OGTT (p<0.05).

CONCLUSION: First-degree relatives and dysglycaemics have reduced glycocalyx thickness related with impaired LV longitudinal, twisting-untwisting function. Postprandial hyperglycemia when combined with insulin resistance causes LV longitudinal dysfunction leading to increased LV twisting.