Sammy, who led West Indies to their second World Twenty20 title earlier this year despite struggling for form, could not find a place in the 13-member squad for the matches at Central Broward Regional Park, Fort Lauderdale on Aug. 27 and 28.
"With regards to Sammy's omission from the squad, the chairman (of selectors) noted that the named-squad was selected purely on players' performances," the West Indies Cricket Board said in a statement.
Chairman of selectors Courtney Browne thanked Sammy, 32, for his contribution and expected Brathwaite, who blasted four successive sixes off a Ben Stokes over in the April 3 World Twenty20 final in Kolkata, would prove an inspiring captain.
"Brathwaite is one of the most talented players in the T20 format of the game and his humble and committed approach to the game can inspire young and upcoming players," he added.
Squad: Andre Fletcher, Andre Russell, Carlos Brathwaite, Chris Gayle, Dwayne Bravo, Evin Lewis, Jason Holder, Johnson Charles, Kieron Pollard, Lendl Simmons, Marlon Samuels, Samuel Badree, Sunil Narine.