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[edit] Cardiovascular Side Effects
SSRIs inhibit cardiac and vascular Na(+), Ca(2+) and K(+) channels and prolong QT intervals. These results suggest that SSRIs have clinically important cardiac as well as vascular effects. Clinicians should be more vigilant about these potential adverse reactions and ECG control may be suggested during therapy, especially in patients with cardiovascular disorders.[7] [8]Vascular resistance is modulated in a complex fashion by serotonin receptors. In healthy people, serotonin causes vasodilation. For example, in the cerebral arteries, the 5-HT1 receptor causes vasoconstriction, which is why sumatriptan succinate (a 5-HT1 agonist) can be used in the treatment of migraine headaches. Serotonin also plays an important role in angina. While serotonin has a vasodilatory effect on normal coronary arteries (an effect that is blocked by the 5-HT2 receptor antagonist ketanserin), serotonin produces direct unopposed vasoconstriction in damaged endothelium. In patients with damaged endothelium (such as those with significant coronary artery disease), it has been speculated that there may be an increase in myocardial ischemia secondary to an increase in vasoconstrictive serotonin in the environment caused by treatment with SSRIs.[9]
In the first 2.5 million patients exposed to fluoxetine, there were reports of 34 cases of atrial arrhythmias, 60 cases of bradycardia, 26 cases of varying degrees of heart block, 54 cases of significant ventricular arrhythmias, 24 cases of congestive heart failure, and 42 cases of other arrhythmias [10]
Cardiovascular events associated with SSRI use include cardiac arrhythmias, orthostatic hypotension, atrial fibrillation, atrial flutter and supraventricular tachycardia. In overdose, fluoxetine has been reported to cause sinus tachycardia, myocardial Infarction, junctional rhythms and trigeminy. However, the total incidence of adverse cardiac effects has been indicated to be less than 0.0003 percent.[11]
The one thing I can find that might affect is the vasodilation part above - that SSRI’s seem to act as vasodilators in some cases, as vasoconstrictors in others. But on the other hand, if the incidence of problems is less than 0.0003 %, it should be OK.