This paper seems to lack rigour. It starts with a premise then does not look at anything that might prove or disprove that premise. Hospital applications were not screened for cannabis use, only Colorado legalised but they used data from the whole western region, most importantly Medicaid also started at the same time as legalisation, do they investigate whether the availability of medical care prompted people to get medical treatment for their existing heart condition? They don't check whether the rise in cannabis use after legalisation was large enough to produce increases of this size across the whole population. An increase larger than the additional users would point to some other cause...
There is a whole website of similar spurious correlations (https://www.tylervigen.com/spurious-correlations). Will they now bring out a paper stating that Nicolas Cage films cause death by drowning? How about Solar power generation in Belize causing Fire inspectors in Florida, which both saw a very highly correlated jump in 2018?
In the way the study is designed, it could also be the non-using spouses having to pick up more work. Or the loss of motivation (and regular aerobic activity) by the users.
It's not totally worthless. It shows that recreational usage may lead to cardiovascular issues. Is it from the THC itself, way of administration, eating crap on munchies or having no motivation to move your ass is something for another paper.
There is a whole website of similar spurious correlations (https://www.tylervigen.com/spurious-correlations). Will they now bring out a paper stating that Nicolas Cage films cause death by drowning? How about Solar power generation in Belize causing Fire inspectors in Florida, which both saw a very highly correlated jump in 2018?