medwireNews: Patients treated for chronic myeloid leukaemia (CML) have a higher risk of arterial and venous vascular events than their counterparts in the general population, suggest the results of a Swedish cohort study.

Of 896 patients diagnosed with chronic phase CML between 2002 and 2012, 94.4% were treated with a tyrosine kinase inhibitor (TKI) and followed up for a median of 4.2 years. The majority of patients received the first-generation TKI imatinib (87.1%), while 26.9% used nilotinib and 23.4% dasatinib.

Each CML patient was matched by age and gender to five individuals in the general population and after 4110 person–years of follow-up, patients had sustained 54 arterial thromboembolic events and 20 venous thromboembolic events versus 185 and 54 events in the controls. This gave a significantly higher relative risk for the two types of events in CML patients, at 1.5 and 2.0, respectively.

In particular, there was a significant excess risk of both myocardial infarction and deep vein thrombosis in the CML patients, with a relative risk of 1.9 and 2.2, respectively, report Torsten Dahlén, from Karolinska University Hospital Solna in Stockholm, and co-workers.

Further analysis indicated that the risk of myocardial infarction with TKI use was higher for patients given nilotinib or dasatinib than those treated with imatinib, with 29 and 19 versus eight events per 1000 person–years, respectively.

However, the researchers caution in the Annals of Internal Medicine that the small number of events in the CML patients and the resulting wide confidence intervals do not allow “meaningful statistical evaluation” for the risks associated with individual TKIs.

And they note that 84% of the 31 patients using TKIs who experienced myocardial infarction had at least one major cardiac risk factor, most commonly hypertension (55%) and angina pectoris (39%).

“Clinicians should be aware of these cardiovascular risk factors when initiating TKI therapy in patients withCML”, the authors therefore recommend.

Acknowledging that their study does not distinguish between the risks of cardiovascular disease driven by CML itself and that associated with its treatment, they add that their “data provide a strong incentive for future studies to identify the mechanisms behind the observed excess risks and to compare the different TKIs with regard to cardiovascular safety.”

By Lynda Wiliams, Senior medwireNews Reporter

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