The following question refers to Section 2.2 of the 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure.The question is asked by University of Colorado internal medicine resident Dr. Hirsh Elhence, answered first by University of Chicago advanced heart failure cardiologist and Co-Chair for the CardioNerds Critical Care Cardiology Series Dr. Mark Belkin, and then by expert faculty Dr. Mark Drazner.Dr. Drazner is an advanced heart failure and transplant cardiologist, Professor of Medicine, and Clinical Chief of Cardiology at UT Southwestern. He is the President of the Heart Failure Society of America.The Decipher the Guidelines: 2022 AHA / ACC / HFSA Guideline for The Management of Heart Failure series was developed by the CardioNerds and created in collaboration with the American Heart Association and the Heart Failure Society of America. It was created by 30 trainees spanning college through advanced fellowship under the leadership of CardioNerds Cofounders Dr. Amit Goyal and Dr. Dan Ambinder, with mentorship from Dr. Anu Lala, Dr. Robert Mentz, and Dr. Nancy Sweitzer. We thank Dr. Judy Bezanson and Dr. Elliott Antman for tremendous guidance.Enjoy this Circulation 2022 Paths to Discovery article to learn about the CardioNerds story, mission, and values.  Question #35 A 50-year-old woman with a history of congestive heart failure, hypertension, type 2 diabetes mellitus, and obstructive sleep apnea presents to the outpatient clinic to follow up on her heart failure management. One year prior, echocardiogram showed an ejection fraction of 30% with an elevated BNP, for which she was started on appropriate GDMT. Repeat echocardiogram today showed an EF of 50%. Which of the following best describes her heart failure status? A HFrEF (HF with reduced EF) B HFimpEF (HF with improved EF) C HFmrEF (HF with mildly reduced EF) D HFpEF (HF with preserved EF) Answer #35 Explanation The correct answer is B – HFimpEF, or heart failure with improved ejection fraction, best describes her current heart failure status. Left ventricular ejection fraction is an important factor in classifying heart failure given differences in prognosis, response to treatment, and use in clinical trial enrollment criteria. The classification of heart failure by EF (adopted from the Universal Definition of HF): –        HFrEF (HF with reduced EF): LVEF ≤40% –        HFimpEF (HF with improved EF): previous LVEF ≤40%, a ≥10% increase from baseline LVEF, and a second measurement of LVEF >40%. –        HFmrEF (HF with mildly reduced EF): LVEF 41%–49%, andevidence of spontaneous or provokable increased LV filling pressures (e.g., elevated natriuretic peptide, noninvasive and invasive hemodynamic measurement) –        HFpEF (HF with preserved EF): LVEF ≥50%, and evidence of spontaneous or provokable increased LV filling pressures (e.g., elevated natriuretic peptide, noninvasive and invasive hemodynamic measurement) Patients with HFmrEF are usually in a dynamic state of improving from HFrEF or deteriorating towards HFrEF. Therefore, patients with HFmrEF may benefit from follow-up evaluation of systolic function and etiology of sub-normal EF. Improvements in EF are associated with better outcomes but do not indicate full myocardial recovery or normalization of LV function. Indeed, structural and functional abnormalities such as LV dilation and systolic or diastolic dysfunction often persist. Moreover, EF may remain dynamic with fluctuations in either direction depending on factors such as GDMT adherence and re-exposure to cardiotoxic agents. As such, the term heart failure with “improved EF” was deliberately chosen over “recovered EF” and “preserved EF”. Importantly, in patients with HFimpEF while on GDMT, the EF may decrease after withdrawal of GDMT. Main Takeaway