I read the article by Nichols et al, recently published online in the American Journal of Cardiology . In their study, the investigators reported that patients with heart failure (HF) with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF) experienced similar adjusted incidence rates, and they suggested that HF can be considered a single entity. Nichols et al identified the prognostic similarity of HFrEF and HFpEF. However, because of some major flaws in design of the study, I would like to make some criticism on methods and findings of the present article.

It is known that medical therapy is the essential prognostic factor of all patients with HF. However, some medications (e.g., angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, aldosterone antagonists, and β blockers) reduce hospitalization rates, mortality, and adverse events in patients with HFrEF than those with HFpEF. Treatment with these drugs may influence the prognosis rather more in patients with HFrEF compared to patients with HFpEF. Hence, conventional medical therapy may play different prognostic role respectively in patients with HFrEF and HFpEF. In this sense, to compare the prognosis of HFrEF and HFpEF, the investigators should clearly state the incidence of treatment with conventional medical therapy for both groups respectively.

In conclusion, HF may have poor prognosis independent of left ventricular ejection fraction. However, treatment and prognostic role of medical therapy varies considerably in HFrEF and HFpEF. Therefore, to identify and compare the prognosis of HFrEF and HFpEF, it should be proven that both groups are similarly treated with recommended medications for these diseases.