There really is no such thing for helicopters, except in the limited context of a specific procedure, where we use Vtoss. For Cat A procedures, the whole thing is included, from the aceleration distance to the angle of climb.
Angle of climb would be 90 degrees for a vertical climb, and would flatten gradually as the gross weight were increased and all other variables held constant (such as wind, alt, temp, engine power assurance margin).
For airplanes, the induced drag at low speeds near stall domnates, so Vx falls in a relatively small band of speed, and so Vx is a useful tool for pilots. It would freak an airplane driver out to know that at 10,000 pounds his Vx was 25, and at 9300 pounds, it was zero., and in fact, he could take off backwards if he was under a cliff, so his climb angle would be maybe 135 degrees.
For helos, the speed for Vx is probably below 25 knots if you can hover IGE, so it is not even registered on the pitot system.
For a helo that can just hover IGE, at 15 knots (just above ETL) it can climb at perhaps 100 feet per minute while advancing forward at 900 feet per minute. The climb angle would be about 6 degrees in that case. If that helo were accelerated to 20 or 25 knots, it might climb at 500 feet per minute, so it would make perhaps 9 degrees of angle, but it would eat lateral distance getting the extra speed, and that might flatten its total angle of climb from the takeoff point. Same is tre going to 60 knots, where its angle might be 12 degrees (with 1500 FPM).
For Cat A, we assume a 35 foot barrier, and show the distance to clear that barrier or the distance to reject and stop short. The Speeds and powers specified in the flight manual cook in some Vx logic.