A study presented by Dr. Murray A. Middleman at the American Heart Association's annual conference on cardiovascular disease in San Diego, showed that smoking marijuana significantly raises the risk of heart attack in people already at risk through heart disease.

Dr. Middleman noted that marijuana's tendency to increase heart rates in reclining smokers, and for those rates to drop precipitously when the individual stands up, may pose significant risks for people with coronary disease. The group studied 3,882 heart attack sufferers, of which 124 were marijuana users. Of those, 37 claimed to have used marijuana within 24 hours of their heart attack, and 9 had used it within the previous hour. The risk, said the researchers, was 4.8 times higher than normal within an hour of smoking, but dropped precipitously to 1.7 times normal risk by the second hour.

An interview follows with Dr. Lester Grinspoon, also of Harvard. Dr. Grinspoon is one of the world's foremost marijuana researchers and is author of several books including the seminal "Marihuana Reconsidered."

WOL: Dr. Grinspoon, what is your assessment of the Middleman report?

Dr. Grinspoon: (Laughs). I've been getting phone calls all week about it. I even spoke with Dr. Middleman this week to ask him for his report. It has not yet been written. In fact, he does have an abstract. Now, let me say that since 1967 there have been numerous reports and studies, each of which the American media has blown out of all proportion, stating one or another supposed ill effect of marijuana use. I can list them, if you'd like. 'Increase in the size of the ventricles, decrease in testosterone, destruction of chromosomes.' All were front-page stories, none of them have ever been replicated. In other words, they didn't pan out scientifically. Of course, the studies that contradicted them ended up on page 31 or thereabouts, if they got mentioned at all.

WOL: So you don't give much weight to Dr. Middleman's findings?

Dr. Grinspoon: Well, I would point out that out of 3,882 patients, we're talking about 9 who used marijuana within an hour of the onset of a heart attack. That's around 0.2%. By sheer mathematics, given that people sleep eight hours per day or so, we can deduce that 6.7% of those patients emptied their bowels within an hour of onset. It's incredible to me that the numbers here could be said to constitute a significant risk factor.

WOL: Dr. Middleman said in an interview that he believes that it is the increased heart rate from smoking marijuana that is responsible.

Dr. Grinspoon: Yes, and he put that increase at 40 beats per minute. In truth, that number is closer to 20 beats per minute, which is probably consistent with running up the stairs in one's house.

WOL: So you disagree with Dr. Middleman's characterization of the risk as 'significant'?

Dr. Grinspoon: First, let me say that I blame the media far more than I do Dr. Middleman. I read his abstract, and in its conclusion he cautioned against making too much of the data. Conceivably, there is some risk, although if there is, it is barely measurable. Even assuming that the data presented is right, one must still wait to see if it can be replicated.

WOL: You seem to be pretty skeptical about the chances of that happening.

Dr. Grinspoon: Well, in 1997, Kaiser Permanente did a large- scale study which included more than 65,000 admitted marijuana users, and they could not demonstrate any impact of marijuana use on mortality. If marijuana use really was a significant risk factor for heart attack, it is hard to believe that it didn't turn up there. Again, I'm not saying that there is absolutely no risk demonstrated here. But given the history of the research since 1967, I'd be surprised if these findings don't go down the same chute as all of the other front-page scare stories.

NOTE: In the April, 1997 edition of The American Journal of Public Health, Dr. Stephen Sidney writes about a long-term (12-year) study undertaken by Kaiser Permanente -- a medical insurer/provider, therefore an entity with a fiduciary interest in the integrity of the results -- into the mortality rates of marijuana smokers. The study population comprised 65,171 subjects aged 15 through 49 years. Conclusion: Marijuana use had little effect on non-AIDS mortality in men and on total mortality in women (Am J Public Health. 1997;87:585-590).

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