A 72-year-old man presented to our clinic with hypertension. Arterial stiffness evaluated by cardio ankle vascular index (CAVI) was markedly increased at 13.5. We treated him using 80 mg/day of valsartan for three months. CAVI was decreased from 13.5 to 13.0. However, his BP fluctuations were still high. We changed the treatment to angiotensin receptor-neprilysin inhibitor (ARNI) with increasing doses up to 400 mg. Independent of the change in blood pressure at the time of measurement, CAVI improved with ARNI dose. Hypertension treatment with an awareness of the cardio-vascular interaction might be a possibility prevents future heart failure development effectively.