Under what condition should the first-arriving ALS company withhold cardiac leads?

The appropriate condition under which the first-arriving ALS company should withhold cardiac leads is if On-Line Medical Control directs otherwise. This situation highlights the importance of communication and protocols in emergency medical services. When medical control is involved, they provide guidance based on the specific situation and patient condition, which can include considerations such as whether the cardiac leads are necessary or appropriate to apply at that moment.

This option underscores the role of On-Line Medical Control in ensuring that interventions follow established protocols and best practices. By prioritizing medical direction, the paramedics can ensure that they are making informed decisions that align with patient care standards and situational requirements.

In contexts where the other options are proposed, they do not provide the same level of reference to established medical authority and protocol, making the medical control option the most fitting choice.