To the Editor In his Viewpoint, Packer1 bemoans the slow uptake of sacubitril/valsartan by US practitioners and delivers an inspirational rallying cry for increased use of this new heart failure medication. That sacubitril/valsartan is the first new class of heart failure therapy with proven mortality benefit in over a decade cannot be understated. While we agree with most of his erudite views, we worry Packer is underestimating the long-term adverse effects of this medication. Foremost among these are concerns for amyloid deposition in the eye and brain, theoretically leading to visual and cognitive impairment. Packer states that even if these adverse events are real, 鈥渢heoretical concerns about toxicity occurring after 10 to 20 years are irrelevant if these durations exceed the lifespans of patients who should be treated with the drug鈥� and that 鈥渋t serves little purpose to speculate about a future that would not exist in the absence of having been treated with the drug.鈥�1