Chronic obstructive pulmonary disease and cardiac comorbidities: A cross-sectional study.

Sir,

We read the article, “Chronic obstructive pulmonary disease and cardiac comorbidities: A cross-sectional study” by Kaushal et al.[1] with great interest. The study is useful as we come across these conditions in day-to-day practice.

During reading of the article, we came across some points which we felt worth discussing.

First, the authors have stated the definition of pulmonary hypertension (PH) as systolic pulmonary arterial pressure (sPAP) >30 mmHg. As per the recommendations of the European Respiratory Society guidelines, the definition of PH >30 mmHg is calculated by the right heart catheterization and not by echocardiography. However, in the present study, the sPAP is measured by echocardiography. Hence, using this value for defining PH is questionable, keeping in mind that PH measured by echocardiography is not fully reliable, especially if lung hyperinflation increases.[2345] Moreover, echocardiography being an operator-dependent procedure between operator variability may be large and will give false high values of pulmonary arterial pressure (PAP).

Second, the authors have not mentioned whether patients with exacerbation of chronic obstructive pulmonary disease or patients recovering from exacerbation were included or not. As it has been reported[67] that during COPD exacerbation the pulmonary arterial pressure rise by 20 mmHg thus if 2 D echo or Rt heart catherization done during COPD exacerbation it can give false high value of PAP. Thus test should be done after stabilization of patient

Last but not the least, authors have calculated the mean duration of smoking in their subjects but have not calculated the association between smoking index and prevalence of cardiac comorbidities. The studies have shown the association of smoking with many cardiac comorbidities, especially PH with a linear correlation.[8]

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