Cannabis and the Heart

Austin

Alright, welcome back to the Hollie.AI Journal Club. I'm Austin, and as always, I'm joined by Hollie. Today, we're diving into a topic that's, well, honestly everywhere these days—cannabis and the heart. Hollie, you ready?

Hollie

Absolutely, Austin. I feel like every other patient note I see lately mentions cannabis use, so this is long overdue. And the new data is, well, a bit sobering, isn't it?

Austin

Yeah, that's putting it mildly. So, let's start with the big numbers. There was this massive retrospective study—over 4.6 million people, which is just wild. They found that cannabis users under 50 were more than six times as likely to have a heart attack compared to non-users. Six times. That's not a rounding error.

Hollie

No, that's a proper signal. And it wasn't just heart attacks, right? The same study flagged higher risks for ischemic stroke, heart failure, and even cardiovascular death among cannabis users. It's not just a one-off finding.

Austin

Exactly. And then, if you look at the frequency side, there was another study—this one from the All of Us Research Program, about 175,000 participants. They found that daily cannabis users had a 34% higher likelihood of developing coronary artery disease compared to non-users. And it looked like the more often you used, the higher the risk. So, it's not just a yes-or-no thing, it's dose-related.

Hollie

That dose-response relationship is always a bit of a red flag for causality, isn't it? I mean, it's not proof, but it does make you sit up and pay attention. And, Austin, I know in Jersey, cannabis use is on the rise. How are you seeing this play out in your own risk assessments?

Austin

Yeah, so, in Jersey, we've got about two thousand daily users, which for our population is actually quite a lot. I've started asking about cannabis use routinely when I'm scoring risk—like, alongside smoking, blood pressure, all the usual suspects. Honestly, I think it needs to be part of the standard risk factor checklist now. It's not just a lifestyle question anymore.

Hollie

And that's a shift, isn't it? I mean, a few years ago, cannabis was almost an afterthought in the clinic. Now, with these numbers, it's hard to justify leaving it out of the conversation.

Austin

So, let's talk about the meta-analysis that just came out in 2025. This one pooled data from over two dozen studies—24, to be exact. They looked at major adverse cardiovascular events, or MACE, so things like heart attack, stroke, and cardiovascular death. The risk ratios were, well, not trivial. For acute coronary syndrome, the risk ratio was 1.29. For stroke, 1.20. And for cardiovascular death, it was over two—2.10, to be precise.

Hollie

Those are meaningful numbers. And, just to clarify, a risk ratio above one means increased risk, so these aren't just statistical blips. But, Austin, what about the quality of the evidence? I know some of these studies were cross-sectional, some cohort, and there was even a case-control in the mix. How robust do you think these findings are?

Austin

Yeah, that's a fair question. The meta-analysis did try to account for confounders—other psychoactive substances, baseline risk, that sort of thing. And when they restricted the analysis to just the cohort studies, the results were pretty similar. So, it's not just a fluke of study design. But, I mean, there are always limitations. Self-reported cannabis use, for one. And, you know, it's hard to fully untangle cannabis from other risk factors—like, are these users also more likely to smoke tobacco, or have other lifestyle risks?

Hollie

Right, and the meta-analysis did mention that. They used the ROBINS-E tool to assess risk of bias, but observational studies always have that lurking confounder problem. Still, the consistency across studies is hard to ignore. And interestingly, one of the included studies focused on medical cannabis, and the risk was still there. So it's not just recreational use.

Austin

Yeah, that's a good point. And, just to add, the composite outcome—combining heart attack and stroke—wasn't statistically significant in the two studies that measured it, but the individual risks were. So, it's not a perfect story, but the trend is pretty clear.

Hollie

And I think that's where we have to be careful. The evidence isn't perfect, but it's strong enough that we can't just ignore it. Especially as cannabis becomes more mainstream, both medically and recreationally.

Austin

So, what do we actually do with all this? For me, it's about making sure we ask every patient about cannabis use, just like we do with smoking or alcohol. It needs to be part of the cardiovascular risk conversation, not an afterthought. And honestly, I think guidelines are going to have to catch up soon.

Hollie

I agree. And, you know, as cannabis use becomes more common, especially among younger adults, the stakes are higher. If we're not asking, we're missing a big piece of the risk puzzle. I think digital tools can help here—surfacing substance use history in the middle of a busy clinic, or even flagging it during acute care. It's a bit like my own origin story, really. I was created to help clinicians catch those details that can slip through the cracks when things get hectic.

Austin

Yeah, and honestly, that's where tech like Hollie.AI really shines. I mean, we've all had those moments—you're in the middle of a consult, and you forget to ask about something crucial. If we can automate those reminders, or at least make them easier to surface, that's a win for patient safety.

Hollie

And it's not just about ticking a box, is it? It's about having a real conversation with patients—explaining that cannabis isn't risk-free, especially for the heart. I think as the evidence grows, we'll see more emphasis on this in both prevention and acute care pathways.

Austin

Yeah, and I guess the takeaway is: don't assume cannabis is benign, especially for the heart. Ask about it, talk about it, and factor it into your risk assessments. Simple as that.

Hollie

Well said. And on that note, I think we'll wrap up for today. Thanks for joining us on the Hollie.AI Journal Club. Austin, always a pleasure.

Austin

Thanks, Hollie. And thanks to everyone listening. We'll be back soon with more edge papers and hot topics in cardiology. Take care, everyone.

Hollie

Bye for now!