Summary by Annie Isaac, UGA PharmD Candidate (’12), Jason M. VanLandingham, PharmD, BCPS
Depression is associated with an increased risk for coronary heart disease in healthy patients and cardiac morbidity and mortality in patients with coronary heart disease. However, little research has been done to determine the role antidepressants play in this risk. This study was conducted among patients with a diagnosis of depression, to determine the long term risk of myocardial infarction (MI) in patients who have taken antidepressants compared with those who have not.
METHODS: This study was conducted retrospectively, among more than 93,000 patients of the Veterans Affairs (VA) who were diagnosed with depression between October 1999 and October 2000. According to VA guidelines, at least 12 weeks of antidepressant therapy should be given for a new episode of depression. Of the patients identified, 78.7% received at least 12 weeks of antidepressants, 12.9% received 1 to 11 weeks of antidepressants, and 8.4% received no antidepressant therapy. Those patients who received at least 12 weeks of antidepressant therapy were the treatment cohort, while those who received less than 12 weeks of antidepressant therapy, or no therapy, were the control. The patients identified were then tracked from October 2000 through September 2007 for MI and cardiac death. The study excluded patients who already had a diagnosis of heart disease or cerebrovascular disease. Also, patients with psychotic and bipolar disorders were excluded, as well as those with a diagnosis of dysthymia. The study was controlled for severity of depression as well as for other risk factors for MI, such as hypertension, diabetes, obesity, and hyperlipidemia. The study was also controlled for individual antidepressants and classes.
RESULTS: The average age of patients in this study was 51, and the population was 86% male. 78.8% of the population was treated with an antidepressant, while the remaining 21.2% had either never taken an antidepressant or had taken one for less than 12 weeks. In this study, significantly fewer patients in the antidepressant treatment group suffered an MI or death, than in the control group. Accordingly, in each class of antidepressants and in each individual drug, the same conclusion held true, that there were fewer MIs than the control group.
DISCUSSION: Among VA patients with a diagnosis of depression, those who used antidepressant drug therapy for at least 12 weeks had significantly fewer MIs and all-cause mortality than those who did not. While earlier evidence showed that depression is a risk factor for heart disease, this study suggests that antidepressants reverses that risk and provide some protection. The mechanism of this protection is unknown. The protective mechanism of SSRIs is generally attributed to its effects on platelet aggregation. Tricyclic antidepressants (TCAs) have been shown in previous studies to have cardio-toxic effects and contribute to arrhythmias. This study showed no cardiac ill-effects associated with TCAs, and showed the same protective effects that the other antidepressants have. Compliance in drug therapy may be a confounding factor in this study. Patients willing to take antidepressants and continuing taking them for at least 12 weeks may also be more compliant with cardiac drug therapy and instructions from their healthcare providers. This alone may explain the link between antidepressant drug therapy and cardio-protection. However, the link this study found should not be ignored and should fuel further study into the cardio effects of depression and the cardio-protective properties of antidepressants.₁
As with any of our Healthy Heart patients, diet, appropriate cardiovascular pharmacotherapy, and exercise should be monitored and/or recommended. As we all know, exercise is extremely beneficial in elevating mood. However, now when we have to rely on antidepressant medication we can be more confident that we are not increasing our patient’s cardiovascular risk. We actually might be decreasing their chances of having a heart attack……that should give them a reason to smile!
₁ “Antidepressant Drug Compliance: Reduced Risk of MI and Mortality in Depressed Patients.” The American Journal of Medicine. Vol. 124. Issue 4. April 2011. pgs 318-324.