Abstract 244: The Relationship of Left Ventricular Untwisting to Diastology in Type 1 Diabetes
BACKGROUND: Left ventricular (LV) torsion followed by untwisting during diastole is an important component that affects LV filling. We used speckle tracking echocardiography to study the early changes in the LV untwisting patterns in patients with uncomplicated type 1 diabetes (T1DM).
METHODS: 33 asymptomatic subjects with T1DM (age 32.9±8.4 y) and 32 age-matched healthy controls (HC) (age 30.8±8.0 y) were recruited. All subjects underwent history, echocardiogram and metabolic exercise testing to exclude heart failure and ischaemic heart disease. LV rotation measurements were made using a commercially available speckle tracking system. In order to adjust for the differences in heart rate between individuals the RR interval was normalised to 100%.
RESULTS: LV ejection fraction was not different in T1DM subjects and HC (60.7±5% vs 61.4±5%, p=0.29). Peak LV torsion was significantly increased in the T1DM as compared to HC (1.9±0.6 0/cm vs 1.4±0.7 0/cm, P<0.01). The early peak LV untwisting rate was similar in T1DM and HC (−11.9±4.6 0/cm/sec vs −11.3±4.7 0/cm/sec, P=0.29). The late peak LV untwisting rate was increased in T1DM (−6.2±3 0/cm/sec vs −4.9±3.9 0/cm/sec, P=0.07) but the difference did not reach statistical significance. The time to early peak untwisting rate was not different (50.9±9.6% vs 48.4±7.3%, P=0.12) but the late peak untwisting rate was significantly delayed in T1DM patients (80.4±12.5% vs 72.7±14.6%, P<0.05). Tissue doppler analysis demonstrated a reduction in E′ (10.6±2 cm/sec vs 12.2±2, P<0.01) and E′/A′ (1.3±0.5 vs 1.6±0.5, P<0.05) with an increase in E/E′ (7.7±1 vs 6.4±2, P<0.001) indicating early relaxation abnormality. Also there was increase in trans-mitral A wave velocity (58.4±15 cm/sec vs 49.1±10 cm/sec, P<0.01) and mitral annular A′ (8.6±2 cm/sec vs 7.8±2 cm/sec, P<0.05).
CONCLUSION: We demonstrate for the first time using speckle tracking that early peak LV untwisting rate is preserved and late peak untwisting rate is increased and delayed in young patients with uncomplicated T1DM. This is associated with early relaxation abnormalities in the LV. The increase in late untwist rate may indicate increased filling due to atrial systole which is also suggested by the finding of increased A wave velocity and A′ on doppler analysis.