Heart failure, CV mortality risk higher with aromatase inhibitors vs tamoxifen

Aromatase inhibitors seem to confer heightened risks of heart failure and cardiovascular (CV) mortality when compared with tamoxifen, a study has found.

The study involved 23,525 newly diagnosed breast cancer patients, among whom 17,922 initiated hormonal therapy with either an aromatase inhibitor (n=8,139) or tamoxifen (n=9,783). Anastrozole was the most commonly used aromatase inhibitor (57.7 percent), followed by letrozole (41.7 percent) and exemestane (0.6 percent).

In Cox proportional hazards models with inverse probability of treatment, aromatase inhibitor vs tamoxifen users had an 86-percent increased risk of heart failure (incidence rate, 5.4 vs 1.8 per 1,000 person-years; hazard ratio [HR], 1.86, 95 percent confidence interval [CI], 1.14–3.03) and 50-percent higher risk of CV mortality (incidence rate, 9.5 vs 4.7 per 1,000 person-years; HR, 1.50, 95 percent CI, 1.11–2.04).

Aromatase inhibitors were also associated with a trend toward heightened risks of myocardial infarction (incidence rate, 3.9 vs 1.8 per 1,000 person-years; HR, 1.37, 95 percent CI, 0.88–2.13) and ischaemic stroke (incidence rate, 5.6 vs 3.2 per 1,000 person-years; HR, 1.19, 95 percent CI, 0.82–1.72). The estimates were robust to several sensitivity analyses.

The higher risk of CV events associated with aromatase inhibitors should be balanced with their favourable clinical benefits relative to tamoxifen, the researchers said.