Mar­i­juana abuse linked to in­creased my­ocar­dial in­farc­tion risk

The Philippine Star - - OPINION - CHARLES C. CHANTE, MD

Mar­i­juana abuse was in­de­pen­dently as­so­ci­ated with an eye-open­ing dou­bled risk of acute MI in a large, ret­ro­spec­tive, age-matched co­hort study, as re­ported at the an­nual meet­ing of the Amer­i­can Col­lege of Car­di­ol­ogy.

The link was strong­est by far in young adult mar­i­juana abusers, with an ad­justed 3.2-fold in­creased risk of MI in 25- to 29-year-olds with mar­i­juana abuse noted in their med­i­cal records, com­pared with age­matched con­trols and a 4.56-fold greater risk among the 30-to 34-year-old cannabis abusers, ac­cord­ing to Case West­ern Re­serve Univer­sity in Cleve­land.

“Our study raises the pos­si­bil­ity (of) an as­so­ci­a­tion be­tween cannabis and MI in­de­pen­dent of age, hy­per­ten­sion, di­a­betes, smok­ing, and abuse of other sub­stances.

These data con­sti­tute a sig­nal war­rant­ing fur­ther re­search. Pub­lic opin­ion re­gard­ing pot­heads has un­der­gone a huge shift. Med­i­cal and/or recre­ational mar­i­juana is now le­gal in 28 states and the District of Columbia. Sur­veys in­di­cate that, in 2015, 8.3% of Amer­i­cans aged 12 years and older had used mar­i­juana dur­ing the pre­vi­ous month, and 13.5% had used it within the past year.

“Car­di­ol­o­gists and other physi­cians are more likely than ever be­fore to en­counter pa­tients who use mar­i­juana or even ask them to pre­scribe it.

The cannabis plant con­tains more than 60 cannabi­noids. Al­though mar­i­juana is widely pre­scribed for treat­ment of nau­sea, anorexia, neu­ro­pathic pain, glau­coma, seizure dis­or­ders, and other con­di­tions, the long-term ef­fects of mar­i­juana on the car­dio­vas­cu­lar sys­tem are largely un­known.

This am­bi­gu­ity was the im­pe­tus for the study. It uti­lized a data­base in­cor­po­rat­ing 26 health care sys­tems across the United States with nearly 50 mil­lion pa­tients, which is main­tained by Ex­plo­rys, an eight-year-old Cleve­land-based com­pany.

It iden­ti­fied 210,700 pa­tients with cannabis abuse noted in their med­i­cal records, cov­er­ing provider/pa­tient en­coun­ters be­tween Oc­to­ber 2011 and Septem­ber 2016. Their mean age was 36.8 years. The abusers were age matched to 10,395,060 non-mar­i­juana abuser con­trols.

The five-year cu­mu­la­tive in­ci­dence of MI in this skewed-young pa­tient pop­u­la­tion was sig­nif­i­cantly higher than in the mar­i­juana abuser group: 1.28%, com­pared with 0.89%, for a 44% in­crease in rel­a­tive risk.

How­ever, the mar­i­juana abusers also had a sig­nif­i­cantly higher bur­den of car­dio­vas­cu­lar risk fac­tors than did their non-cannabis abus­ing coun­ter­parts. They were 2.85 times more likely to have hy­per­ten­sion, 1.59 times more likely to be dys­lipi­demic, and 7.2 times more likely to be cig­a­rette smok­ers, and they had a 2.8 times greater preva­lence of di­a­betes. Of note, they were also 17.6 times more likely to abuse co­caine.

In a mul­ti­vari­ate anal­y­sis ad­justed for these and other po­ten­tial con­founders, mar­i­juana abuse re­mained in­de­pen­dently as­so­ci­ated with a 1.73 fold in­creased risk of acute MI. More­over, af­ter elim­i­nat­ing pa­tients with known coro­nary artery dis­ease, the strong­est risk fac­tor for MI, from the anal­y­sis, mar­i­juana abuse was in­de­pen­dently as­so­ci­ated with a twofold in­creased risk of MI.

This was a ret­ro­spec­tive study, one lim­i­ta­tion of which was the stan­dard caveat re­gard­ing the pos­si­bil­ity of un­rec­og­nized con­founders that couldn’t be taken into ac­count.

An­other study lim­i­ta­tion is the un­cer­tainty re­gard­ing the di­ag­no­sis of “cannabis abuser” in pa­tients’ charts. The Ex­plo­rys cloud-based data­base re­lies on ICD codes to cap­ture data. It doesn’t in­clude spe­cific in­for­ma­tion on how much mar­i­juana a pa­tient who was la­beled as an abuser was ac­tu­ally us­ing. This lim­i­ta­tion raises an unan­swered ques­tion: Were young adults who abused mar­i­juana at high­est risk for MI be­cause of heav­ier use, or are younger pa­tients’ coro­nary ar­ter­ies some­how more vul­ner­a­ble to mar­i­juana’s po­ten­tial ad­verse car­dio­vas­cu­lar ef­fects?

Sev­eral au­di­ence mem­bers called the study “very provoca­tive.”

It was said that the fun­da­men­tal ques­tion in the mind is whether the car­dio­vas­cu­lar haz­ard of mar­i­juana iden­ti­fied in this study is the re­sult of the prac­tice of smok­ing the raw prod­uct, usu­ally, as­so­ci­ated with il­licit mar­i­juana abusers.

To­day, le­gal­ized mar­i­juana is of­ten con­sumed in the form of ed­i­ble prod­ucts, tinc­tures, and other de­riv­a­tives that don’t in­volve smoke in­hala­tion. Do these al­ter­na­tive forms of con­sump­tion pose any car­dio­vas­cu­lar risk, es­pe­cially in this era of wide­spread de­crim­i­nal­iza­tion of cannabis? it was asked.

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