Bedeutung laborchemischer und echokardiographischer Parameter in der Diagnostik der Zentralen Schlafapnoe bei Patienten mit Chronischer Herzinsuffizienz

Cheyne-Stokes respiration is present in up to 40% of patients with chronic heart failure [CHF] and is considered to be an independent risk factor for increased overall mortality. In this study we examined the use of brain natriuretic peptide plasma levels to predict CSR in patients with chronic heart failure. In order to do this, overnight polygraphy and cardiac work-up were performed and neurohumoral activation was determined in 102 consecutive patients with CHF. Since RV function has considerable influence on the prognosis of patients with CFH, additional 2D echocardiography and tissue velocity imaging were performed in a subpopulation of 42 consecutive patients with CHF to examine whether CSR is associated with right ventricular dysfunction. While demographic characteristics did not significantly differ among patients with (n=38) or without CSR (n=64), BNP- and norepinephrine levels were significantly increased in patients with CSR. Moreover, BNP concentrations were significantly associated with the central apnea-hypopnea index. The area under the ROC curve that used BNP to predict CSR was 0,780. Using clinically esablished cut-off limits of BNP plasma levels, heart failure patients with BNP levels > 500 pg/ ml displayed a 13 fold increased risk of CSR compared to patients with BNP levels < 100 pg/ml. In multiple logistic regression analysis paCO2 (point estimate 0.84, 95% CI: 0.72 to 0.98; p = 0.02) and higher BNP class (point estimate 3.14, 95% CI: 1.38 to 7.144; p = 0.006) emerged as parameters independently predicting the presence of CSR in our cohort of CHF patients. Echocardiographic evaluation revealed a significantly reduced velocity of the tricuspid annular systolic motion [TASM], a parameter reflecting systolic RV function, in CHF patients with CSR (10.5 +/- 2.3 cm/s) compared to those without CSR (15.0 +/- 5.1cm/s; p=0.004). In addition, TASM was inversely associated with the CAHI (y = 15.2 - 0.2x; r = 0.46, p = 0.003). RV dimensions were significantly increased and the fractional RV area changes were significantly reduced in CHF patients with CSR (33+/-17 vs. 48+/-20%; p=0,04). Doppler parameters of pulmonary artery flow indicate higher pulmonary artery pressures in CSR patients compared to patients without CSR, which is also reflected by an increased RV free-wall thickness in CSR patients (6,5+/- 1,1 vs. 5,3+/- 1,3 mm; p = 0,05). In conclusion, CSR is significantly associated with neurohumoral activation in CHF patients. Specifically, BNP levels are associated with the severity of cardiac and sleep related desease and may be of additional help in the detection of CSR and more appropriate use of polysomnography in patients with chronic heart failure. Furthermore, CSR is associated with depressed systolic RV function and increased RV dimensions in CHF patients. In future it should be examined whether optimized treatment of CSR will also improve RV function and lead to a better prognosis of CHF. Concerning this matter, current studies show partly controversial results.