Effects of continuous positive airway pressure therapy on left ventricular function assessed by tissue Doppler imaging in patients with obstructive sleep apnoea syndrome

AIMS: In this study, we aimed to assess left ventricular (LV) systolic and diastolic functions by tissue Doppler imaging (TDI) in patients with obstructive sleep apnoea syndrome (OSAS) and to investigate the effects of 6 month continuous positive airway pressure (CPAP) on LV systolic and diastolic functions. METHODS AND RESULTS: We studied 28 new diagnosed moderate and severe OSAS patients (apnoea-hypopnoea index >15) and 18 control group. Exclusion criteria were the presence of structural heart disease, pulmonary disease, diabetes mellitus, dyslipidaemia, alcoholism, neuromuscular disease, renal failure, or malignancy. They were not previously considered or treated for OSA and were all free of drugs. Left ventricular lateral and septal wall early myocardial peak velocity (Em), late myocardial peak velocity (Am), Em to Am ratio, myocardial relaxation time (RTm), myocardial systolic wave (Sm) velocity, isovolumic acceleration (IVA), myocardial pre-contraction time (PCTm), contraction time (CTm), and PCTm to CTm ratio were measured. All echocardiographic parameters were calculated 6 months after CPAP therapy. No statistically significant difference was detected between the groups according to age, gender, body mass index, systolic and diastolic blood pressure, heart rate, fasting blood glucose, and serum lipid parameters. Left ventricular systolic parameters, such as LV septal and lateral wall IVA, CTm, and PCTm to CTm ratio, were significantly lower and Sm was similar in patients with the OSAS group compared with the controls. Left ventricular diastolic parameters, such as LV septal and lateral wall Em velocity and Em to Am ratio, were significantly lower; RTm was significantly prolonged; and Am velocity was similar in patients with OSAS compared with the controls. At the end of the treatment, 20 of 28 patients were compliant with CPAP therapy. Left ventricular septal and lateral wall Em velocity, Em to Am ratio, IVA and CTm, and PCTm to CTm increased significantly, PCTm, PCTm to CTm ratio, and RTm decreased significantly after the therapy, whereas Sm velocity and Am velocity did not change after CPAP therapy in compliant patients. CONCLUSION: Left ventricular systolic and diastolic dysfunctions were determined in patients with OSAS, and it was demonstrated that LV systolic and diastolic dysfunctions improved with 6 month CPAP therapy.