The duration of action of Succinylcholine is determined by its metabolism by plasma cholinesterase. So if there is abnormal plasma cholinesterase (=psuedocholinesterase), it will lead to delayed metabolism of succinylcholine as well as mivacirum, heroin, and cocaine.

https://www.youtube.com/watch?v=WGWFFN01qkA succinylcholine usually has v fast duration of action bcuz metabolized by plasma pseudocholinesterase. With atypical pseudocholinesterase, decreased metabolism of succinylcholine and thus causes a prolonged duration of action of succinylcholine ----> APNEA

Not sure about this, but it seems to me that this is referring to "pseudocholinesterase inhibitor deficiency. It's an enzyme defect that is triggered by NMJ blockers - succinylcholine or curare's.

https://en.wikipedia.org/wiki/Pseudocholinesterase_deficiency