Central but not obstructive sleep apnea can be influenced by cardiac resynchronisation therapy

Rationale: This study investigates the influence of cardiac resynchronization therapy (CRT) on sleep disordered breathing (SDB) in patients with severe chronic heart failure (CHF). Methods and Results: A total of 100 consecutive patients with CHF eligible for CRT (NYHA class III, LBBB, QRS width 150 ms, EF 35%, LVEDD 60 mm) were screened for SDB using cardiorespiratory polygraphy (Embletta®) before device implantation. Mean age 64.8 9.8 years, CAD n 42, DCM n 54, valvular heart disease n 4, mean EF 25.7 6.8%, mean VO2peak 13.4 4.8 ml/kg/min, mean QRS width 185 18 ms. Central sleep apnea (CSA) was documented in 39 patients (39%) and obstructive sleep apnea (OSA) in 34 patients (34%). Only 27 patients (27%) had normal results during cardiorespiratory polygraphy. Twenty-two patients with CSA (central apnea index 15/hr) and 8 patients with OSA were reinvestigated 12 24 weeks after biventricular pacemaker implantation for apnea-hypopnea-index (AHI), NYHA classification, and peak oxygen uptake. Eleven patients demonstrated a significant improvement of CSA by CRT: AHI 32.0 vs 10.8, p 0.0001, EF (23.1 vs 27.8%, p 0.026), NYHA (2.9 vs 2.1 p 0.0002), and oxygen uptake (13.7 vs 17.4, p 0.01). In contrast, CSA remained unchanged in the other 11 patients (AHI 33.9/hr vs 30.7/hr, ns). All nonresponders were also nonresponders with respect to CRT (neither improvement of NYHA, EF nor of oxygen uptake after 3 months of CRT). OSA was not influenced by CRT (AHI 14.0 versus 12.0, p ns), despite good clinical response to CRT (NYHA 3.1 versus 2.3; VO2peak 13.7 versus 17.6 ml/kg/min, p 0.02). Conclusion: In appr. 50 % of patients with CRT, a short term improvement of heart failure symptoms and parameters correlates with a marked improvement in central sleep apnea. In patients who do not show a clinical improvement during the first 3 months of CRT, CSA does also not improve, which supports CSA being a marker for the severity of CHF. In contrast OSA is not influenced by CRT. Because of its pathophysiologic and prognostic significance and the availability of modern treatment options, cardiorespiratory screening should be routinely implemented in the evaluation of CRT patients.