, endocrinol- ogists or nephrologists) to guide clinical management. 5. In all cases, patient preferences and values, in part- nership with evidence-based clinical judgment, should guide clinical decision-making. 6. At any point in time, these suggestions and algorithms may be superseded by new data. ACC/AHA Stages of HF: n Stage A: At high risk for HF but without structural heart disease or symptoms of HF. n Stage B: Structural heart disease but without signs or symptoms of HF. n Stage C: Structural heart disease with prior or current symptoms of HF. n Stage D: Refractory HF requiring specialized interventions. GDMT: Guideline-directed medical therapy, repre- senting treatment options supported for use by clinical practice guidelines. HFrEF: Clinical diagnosis of HF and LVEF #40%. New York Heart Association (NYHA) functional classi cation: n Class I: No limitation of physical activity. Ordinary physical activity does not cause symptoms of HF. n Class II: Slight limitation of physical activity. Comfort- able at rest, but ordinary physical activity results in symptoms of HF. n Class III: Marked limitation of physical activity. Comfortable at rest, but less than ordinary activity causes symptoms of HF. n Class IV: Unable to perform any physical activity without symptoms of HF, or symptoms of HF at rest. Optimal therapy: Treatment provided at either the target or the highest-tolerated dose for a given patient. Target dose: Doses targeted in clinical trials. 4. PATHWAY SUMMARY GRAPHIC Figure 1 is an update of the 2017 ACC ECDP Summary Graphic outlining the 10 pivotal issues about HFrEF. Maddox et al. J 5. DESCRIPTION AND RATIONALE: ANSWERS TO 10 PIVOTAL ISSUES IN HF 5.1. 