A 72-yeаr-оld оutpаtient client with chrоnic heаrt failure with reduced ejection fraction (HFrEF, EF 32%) returns to the cardiology clinic after 2 weeks of therapy with metoprolol succinate (Toprol XL) 25 mg PO daily. The client was initiated on the medication at the last visit as part of guideline-directed medical therapy for HF. Current assessment findings: BP: 88/42 mm Hg (baseline 128/76) HR: 59 bpm, regular RR: 18 SpO₂: 96% on room air Lungs: clear to auscultation 2+ pitting pedal edema bilaterally (was 3+ at initiation) Weight: 1.8 kg decrease over 2 weeks Client reports improved exercise tolerance but has had two episodes of mild dizziness when rising from a chair this week Which assessment finding is most important for the nurse to report to the healthcare provider?