Congestive heart failure may coexist and aggravate the non-cardiogenic pulmonary edema of acute respiratory distress syndrome (ARDS). Yet, patients with congestive heart failure are likely under-represented in ARDS trials. We aimed to explore the temporal trends of representation and mortality of patients with comorbid congestive heart failure in ARDS randomized controlled trials. We also explored whether the association between congestive heart failure and mortality depends on age.

We conducted a secondary analysis of individual patient-level data from participants in six ARDS Network and PETAL Network randomized controlled trials. The two most recent, but not the earliest, trials included patients with New York Heart Association (NYHA) IV cardiac failure.

Of 3800 patients with ARDS, 240 (6.3%) had congestive heart failure. Representation of patients with congestive heart failure increased over time ( p   <  0.001), while the difference in mortality between patients with and without congestive heart failure remained unchanged ( p  = 0.317). The association between congestive heart failure and 90-day all-cause mortality did not depend on age ( p  = 0.669 for the interaction).

Representation of patients with congestive heart failure in ARDS randomized controlled trials increased over time, potentially through the inclusion of frail patients with more advanced disease and due to changing diagnostic criteria of congestive heart failure. Mortality did not change over time, and its association with congestive heart failure did not depend on age. The findings of the present study are intended to be exploratory and highlight the need for future prospective studies with standardized definitions and careful patient phenotyping.