Witnesses said his van overtook two vehicles northbound on the M6 and then swerved before ploughing into a railway bridge.
Shortly afterwards, David and Michelle Statham, and their four children, were killed when a lorry ploughed into their people carrier as they queued in tailbacks.
Pathologist Dr Paul Simcock said Mr Myers suffered only minor cuts to his head in the crash, but that his heart was twice the normal size.
He said that toxicology reports found traces of paracetamol, codeine, amphetamine and anabolic steroids.
Coroner Nicholas Rheinberg recorded that Mr Myers died of natural causes to which amphetamine and anabolic steroid use contributed.
