I happen to be an Electrical Engineer and I have a pacer / defibrillator. A lightning strike could induce voltages into pacemaker leads which the pacemaker could detect as an irregularity. However, the pulse is of short duration and high frequency and should have no lasting impact. If you were extremely close to a strike the induced voltages and step voltages ( voltage difference between your feet due to current flow in the ground) could be significant, damaging the pacemaker and maybe killing you. That can be said for people without pacemakers too. Devices that generate " lightning" or sparks should be stayed away from if you have a pacemaker or defibrillator. These are things like Vandergraph generators, Tesla coils, sometimes neon sigh ballasts are used to generate " Frankenstein effects" or electric welders. The pacemaker or defibrillator can pick up the electromagnetic interference and interpret that as sustained heart irregularities. In my case, if I see sparks flying I'm running or more honestly a very determined walk - away from the source. The defibrillator will make you remember the tune " You Light Up my Life" if it thinks your having problems. Newer pacemakers are reportedly less susceptible to electromagnetic interference. I believe they are using shielded leads but I'm not absolutely sure.