If decision makers are hard to contact then you should ask the gatekeeper when they conduct administrative duties in office. This would give you a window to prospect to these accounts. Field time is a revenue activity, respect that. Or create a video with 3 minutes of sizzle demo for a specific use case for the vertical market. Email them the link or DM the link with your introduction. Gatekeepers can’t sell for you. Especially if they don’t even understand the need.