I do note though, in the study, that the important summary Table 1 shows percentages for heart attack ("myocardial infarction") as 3.6% (3.1–4.1) for daily cannabis users, 2.9% (2.6–3.3) for non-daily cannabis users, and 3.7% (3.6–3.8) for non-cannabis users.
Other factors must be taken into account, then, to result in the study's final claim, because obviously, 3.7% is more than 3.6%. Other factors (also reflected in Table 1) such as obesity - 25.5% for daily cannabis users, 33.0% for non cannabis users - and diabetes - 6.1% for daily cannabis users, vs 11.2% for non cannabis users (!).
But those other factors are not exactly negligible, in the bigger picture. Quiet the opposite, one must surmise. There also seems to be a good deal of self-reporting behind the study, which I must assume brings with it a lot of confounding factors such as the socioeconomics of diagnosis ("more affluent people are more likely to have an official diagnosis"). There does seem to be a lot going on here.