Four hearts on the river, he leads

ATs is a clear raise from the BTN in an unopened pot: it has strong equity, suited playability, and will usually act in position after the flop. At 50bb, it also has enough depth to realize its straight, flush, and top-pair potential effectively.

From the BTN in an unopened pot, the raising range is very wide: every pair and ace appears, along with most suited hands and many offsuit broadway, king-high, and connected hands. Suited and connected holdings are favored near the lower edge because they can make stronger postflop combinations, while the weakest disconnected hands are mostly folded. Several borderline hands mix between raising and folding, creating a gradual boundary rather than a sharp cutoff. In general, this width reflects the BTN’s positional advantage and the opportunity to win the blinds immediately.

Betting 1.5BB leverages top-pair value while using in-position pressure to charge draws and weaker made hands without overinflating the pot.

A large bet of 8.5BB can apply pressure while charging hands drawing against top pair, while checking back uses position for pot control on a completed-flush turn and preserves showdown value.

In general, calling lets you use two pair as a bluff-catcher while keeping the opponent’s bluffs in on this four-heart river.