Response to Letter Regarding Article “Sleep and Exertional Periodic Breathing in Chronic Heart Failure: Prognostic Importance and Interdependence”
We thank Dr Guazzi for his interest in our article.1 In our study, a distinct hierarchical prognostic impact of breathing disorders in chronic heart failure patients is evident, and as a unique finding, apnea/hypopnea index (AHI) >30/h alone has a preeminent predictive role in the presence of exercise oscillatory ventilation (EOV), which could be used as an argument for a reinterpretation of previous reports.2,3 Even so, EOV contributes to a meaningful increase of risk in patients with AHI >30/h, and the fact that there were few EOV-alone patients in our population confirms the strong clinical interdependence between EOV and AHI >30/h. At the same time, as stated in the Limitations section of our article, because of the small number of EOV-alone patients, our study should not be viewed as the final word but rather as an encouragement for other centers to examine the prevalence and cardiovascular risk associated with EOV alone. Moreover, the lower mean V̇e/V̇co2 slope value and its reduced prognostic significance are easily explained by the characteristics of the study population: a large number of clinically stable chronic heart failure patients on β-blockers, who exhibit such features.4,5 Finally, with regard to the methodological issues raised by Dr Guazzi, in our experience the influence of EOV on V̇e/V̇co2 slope is negligible.
In conclusion, we believe that neither of these issues has an impact on the main findings of our article and our conclusions are supported by the evidence provided.
Corrà U, Pistono M, Mezzani A, Braghiroli A, Giordano A, Lanfranchi P, Bosimini E, Gnemmi M, Giannuzzi P. Sleep and exertional periodic breathing in chronic heart failure: prognostic importance and interdependence. Circulation. 2006; 113: 44–50.
Leite JJ, Mansur AJ, de Freitas HFG, Chizola PR, Bocchi EA, Terra-Filho M, Neded JA, Lorenzo-Filho G. Periodic breathing during incremental exercise predicts mortality in patients with chronic heart failure evaluated for cardiac transplantation. J Am Coll Cardiol. 2003; 41: 2175–2181.