Subclinical Right Ventricular Dysfunction in Type 2 Diabetes Mellitus: An Echocardiographic Strain/Strain Rate Study

Abstract
Background: Type II Diabetes Mellitus (DM) was accom-panied by subclinical impairment of Right Ventricular (RV) systolic dysfunction. Two-Dimensional (2D) Speckle Tracking Echocardiography (STE) allows a precise evaluation of myo-cardial function.
Aim of the Study: The aim of this study was to assess the RV systolic function in asymptomatic normotensive subjects with type II DM compared with control subjects, using strain/ strain rate qualification by 2D STE.
Subjects and Methods: Prospective study enrolled 100 subjects, they were classified into two groups: Group I included seventy subjects known to have type II DM (36 males and 34 females), mean age 41.37±4.72 years, and group II included thirty healthy subjects (15 males and 15 females) with mean age 39.40±3.14 years. All subjects had normal Left Ventricular (LV) Ejection Fraction (EF), calculated by conventional 2D Trans-Thoracic Echocardiography (TTE). Subjects who had diseases affecting LV and RV systolic functionwere excluded as hypertension, coronary artery disease, valvular diseases, arrhythmias, pulmonary diseases and pulmonary hypertension. All studied population were subjected to informed verbal consent, full history taking. General and cardiac examination were done. Resting standard 12-leads Electrocardiogram (ECG) has been recorded for analysis. HaemoglobinA1c (HbA1c %) level was measured for group I. 2D TTE and 2D STE were done for all subjects. LV global longitudinal strain (LVGLS%), RVGLS%, RV segmental peak Longitudinal Systolic Strains (LSS%) and RV segmental longitudinal systolic strain rates (LSSRs 1/sec) were assessed by 2D STE. Data were collected and statistically analysed.
Results: Both groups showed no statistically significant difference regarding LV linear internal dimensions, EF, LV Mass Index (LVMI), RV inflow linear dimensions, Fractional Area Change (FAC) and Tricuspid Annular Post-Systolic Excursion (TAPSE). Mean values of LVGLS and RVGLS were significantly lower in group I than in group II, as mean values for GLS of LV & RV were (–19.93±1.48, –21.49±3.80 for group I respectively versus –22.10±1.21, –26.40±2.86 for group II respectively) with (p-value <0.001). The mean values of RV segmental LSS were lower in group I than in group II as mean values for basal septum, mid septum, apical septum, basal RV free wall and apical RV free wall were lower in group I. (–14.81±4.02, –16.77±3.66, –18.20±3.42, –20.53± 2.14, –24.41±5.72 respectively) versus (21.03±1.35, –22.73± 2.00, –24.60±1.94, –30.37±3.11, –30.23±5.45 respectively) for group II, (p-value <0.001), except for mid RV free wall which showed no statistically significant difference between both groups. No statistically significant difference between both groups was detected regarding mean values of RV seg-mental (LSSRs 1/sec), except for apical RV free wall which were significantly lower in group I (1.18±0.54) than in group II (1.48±0.54), (p-value=0.022). There was a reverse correlation between GLS of LV and RV with the duration of diabetes and the level of HbA1 C.
Conclusion: Subjects with type II DM were associated with subclinical LV & RV systolic dysfunction compared with control subjects.