Drs. Carilli and Seiden present work that amplifies our findings. The results were based on pulmonary considerations (eg, severity of nonasthmatic airway obstruction), whereas ours were from a cardiac perspective, that is, P waves under changing COPD severity respond dynamically, and the “P pulmonale” is the extreme of the response occurring, as is the case in their data in about 15% of cases. Hitherto (ie, since 1935), P pulmonale has been considered to be a dichotomous variable, whereas our results demonstrate that the P wave in such patients is a continuous variable. The further discussion by Carilli and Seiden is very much on point and contributes to our understanding.