Well, the 5 trumps should have some nuisance value
More to the point, if partner's 2
♥ bid meant something specific, like a limit raise in spades, then I'm clearly passing. I've already (over)bid my hand, and partner has bid his hand (and won't take action over 4
♠). But, if partner's 2
♥ bid was general strength, which is what the OP said, then I think I'm closer to beating 4
♥ than making 4
♠, and partner will do *something* over 4
♥. IOW, I'm playing partner for general strength and a shape like 3-1-4-5, rather than a heart void and 4-0-4-5. If partner has that hand, he should raise spades to whatever level he thinks is appropriate, instead of messing around with a cue bid.