Since this came out I actually came to find quite a nice range of articles that clarify the effects of weed in the heart. And it's not questionable at this point that weed does affect the heart, and it's well known that when under the effects your heart rate will be higher than when sober.
Prevalence of heart failure, cerebrovascular accident (CVA), coronary artery disease, sudden cardiac death, and hypertension were significantly higher in patients with cannabis use. After multivariate regression adjusting for age, sex, hypertension, diabetes mellitus, hyperlipidemia, coronary artery disease, tobacco use, and alcohol use, cannabis use remained an independent predictor of both heart failure (odds ratio = 1.1, 1.03-1.18, P < 0.01) and CVA (odds ratio = 1.24, 1.14-1.34, P < 0.001).
Source:
https://pubmed.ncbi.nlm.nih.gov/29879084/
Notice how they've adjusted the results for the major issues in previous studies of particular relevance: tobacco use and alcohol use.
When compared with nonusers, cannabis users were younger, more likely to be female, and black. Users were also more likely to have chronic lung diseases, chronic liver disorders, depression, obesity, psychiatric disorders, alcohol abuse, and tobacco use.
However, cannabis users were less likely to have AF, hypertension, diabetes mellitus, chronic kidney disease, rheumatologic disorders, and peripheral arterial disease.
Thus, we used a 1:1 matching ratio of case to control, resulting in matched 3,548 non–cannabis users to get a final size of 7,096 records. There were no significant differences in baseline characteristics between the 2 groups of the population other than valvular heart disease and electrolyte derangement, which were more common in cannabis users.
For the 2014 unmatched data, cannabis users are less likely to have AF (19.09% vs 40.26%; p <0.0001) with a significantly reduced unadjusted odds of AF (COR 0.35 [0.32 to 0.38] p <0.0001). After introducing demographic, patient-related, and hospital-related variables, the adjusted OR was attenuated; however, there were still significant reduced odds of AF in cannabis users (AOR 0.85 [0.78 to 0.93], p = 0.0005).
AF is arterial fibrillation. Note how there are significant differences in cannabis users and non cannabis users regarding heart related conditions. While some things seem positive, and others negative it's not questionable that weed does affect your heart in ways we do not yet fully comprehend. This second study has a limited population though and as such will not represent well the general population since it was done on people that have been hospitalized for heart failure.
Also note that the second study correlates data not adjusting for other variables as effectively as the previous one resulting in an independent indicator.
Second study source:
https://www.ajconline.org/article/S0002-9149(18)30383-7/fulltext
EDIT: Cannabis, like any other comparable consumable is a drug, and being legal has no correlation to how dangerous it is, but is a result of the political, economical and social pressures that you see in the world. Recent studies are bringing light to this and that's a great plus. But as any drug, you have to be aware that there are consequences to consuming it and as said many times here, moderation is key. Defending something blindly is the first clue that you need to re-assess your ideals. You can consume possibly harmful things and recognize they are possibly harmful. Data seems to indicate, like with any other drug on the planet that it can be harmful, you only need to spend some time reading research papers.
Being harmful does not mean you cannot consume it and it does not mean that the balance from consumption is always negative. But being aware of this instead of blindly defending it to protect your ideals shows the level of awareness that most people fail to have.
War on drugs and anti-war on drugs is propaganda, with no scientific value whatsoever. There is a correlation between cannabis use and heavier drugs, particularly in studies pre-legalization, but in no way does this mean that cannabis is responsible. People bathe every day, but that doesn't mean you can say having a daily bath kills people because everyone bathes and everyone dies. Correlation is not causation.
While there was a lot of anti-weed propaganda in the past, now it's turned to the opposite and everyone claims that weed is the best thing because they want to sell it, not because it is safe. For the last time, knowing the risks is mandatory, accepting the risks is mandatory and that's why moderate consumption is key.
When evaluating a medical condition you need to account for placebos. You thinking something works for you doesn't mean it actually does and even if it does it doesn't exclude the possibility of it being a mental process resulting from your belief that it actually works. To know the difference science runs double blind tests, which have a control group and two other groups one of which they test for placebo. There is no such study that I have found that places cannabis as a good treatment for any heart condition.
Need not trust me, or the news, or people who defend their consumption habits with half baked arguments, or people that evangelize the substance as if cannabis deserved a first place in the drug podium, if you have doubts, just read:
cannabis harmful - Search Results - PubMed
pubmed.ncbi.nlm.nih.gov
Fortunately, science does not allow room for interpretation, or lies. All interpretation is classified as such in the articles and all the data must be made available so that the article can be peer-reviewed and scientists can replicate the results.
By the way, I often consume cannabis and said all this about it. I don't pretend it's an healthy habit, I don't blindly recommend the substance, I don't pretend it cures anything to justify my habits, I don't pretend I don't need to heavily control myself to prevent becoming overly dependant on it.