The safe psychopharmacological treatment of cardiac patients requires consideration of three main issues: (
1) the cardioactive effects of psychiatric medications; (
2) the interaction of psychotropic medications with other medications the patient is taking or is likely to be prescribed; (
3) the impact of any comorbid health problems. All of these factors must be taken into account when deciding on which psychotropic medications to use in patients with cardiac disease.
Antidepressants
Except in the case of severe CHF causing reduced cardiac output, hepatic congestion, and renal impairment, the absorption, metabolism, and elimination of psychotropics other than lithium is generally not substantially impaired. Therefore, antidepressants must be used in therapeutically effective doses and not reduced unnecessarily for mild CHF.
Tricyclic antidepressants
Tricyclic antidepressants have many properties that make them relatively less desirable for use in cardiac patients. They cause cardiac conduction delays, including bundle-branch block or complete atrioventricular nodal block, and in overdose they may cause ventricular arrhythmias. Tricyclics are class IA antiarrhythmic agents, which prolong atrial and ventricular depolarization, causing increased P-R, QRS, and QT intervals. Studies have shown that QTc intervals of over 440 ms, and especially over 500 msec, are associated with an increased risk of sudden death (
165,
166). Class IA antiarrhythmic agents have been proven to increase mortality in post-MI patients with premature ventricular contractions (
167,
168).
Tricyclics can also cause significant orthostatic hypotension and tachycardia due to α
1-adrenergic blockade. Patients with CHF are often on other medications that cause orthostatic hypotension, such as diuretics and vasodilators, and the risk of falling and sustaining fractures can be significant for elderly patients. Tachycardia increases cardiac demand in general and reduces left ventricular filling time, worsening diastolic function. Nortriptyline and desipramine tend to have fewer anticholinergic side effects and are better tolerated by cardiac patients than tertiary-amine tricyclics such as amitriptyline or doxepin (
169–
171).
Given their effects, tricyclic antidepressants should be avoided whenever possible in patients with recent MI and should not be considered first-line agents for patients with ischemic heart disease or preexisting intraventricular conduction delays. In certain patients, the benefits may outweigh the risks, so consideration should be given to the entire clinical situation (
172). When tricyclics are prescribed for patients with cardiac disease, orthostatic blood pressure measurements should be obtained at baseline and during treatment. A baseline ECG should also be obtained, and follow-up ECGs should be obtained when a therapeutic level of the drug has been reached to evaluate the P-R, QRS, and QTc intervals and to monitor for bundle-branch block or complete atrioventricular block (
173).
Selective serotonin reuptake inhibitors
SSRIs have few cardiac effects in healthy patients. They can cause slowing of heart rate by a few beats per minute, which is usually clinically insignificant (
174). A number of studies have confirmed that, overall, SSRIs carry little or no risk of increasing the QTc interval or causing other ECG changes (
175–
177). Nonetheless, a few case reports have been published of significant sinus bradycardia, dysrhythmias, syncope (
178), and QTc prolongation (
179) in patients taking SSRIs.
In studies of patients who have preexisting cardiac disease, SSRIs have been found to have minimal negative effects on blood pressure or cardiac conduction. Until recently no randomized controlled trials with SSRIs and a placebo or an alternative treatment group with more than 81 total patients had been published (
180,
181). The SADHART study, with 369 patients, was the first large randomized controlled trial to examine the effects of an SSRI, sertraline, in patients with depression after an acute coronary event. The study found that there was no effect of sertraline on heart rate, blood pressure, arrhythmias, ejection fraction, or cardiac conduction (
152). Sertraline was found to be an effective treatment for depression, demonstrating a weak response in the overall sample but a very good response in the groups with severe and with recurrent major depressive disorder. Another small study showed a statistically significant 7% improvement in ejection fraction in patients with preexisting cardiac disease taking fluoxetine (
182).
Cardiac effects of SSRIs may be dose dependent and vary from drug to drug. In a review of 6,000 ECGs of 1,789 patients treated with citalopram in clinical trials, no evidence was found of QTc prolongation (
174). Studies of patients who have taken overdoses of various SSRIs indicate that in overdose citalopram causes significantly greater QTc prolongation than other SSRIs (
183,
184). This may be related to the finding that citalopram inhibits cardiac sodium and calcium channels in animal studies (
185). While very large doses (400 mg or more) were required to produce QTc prolongation in healthy patients, these data would suggest that, in general, extremely high doses of citalopram should be used with careful monitoring in cardiac patients, particularly those who are also taking inhibitors of cytochrome P450 enzyme 2C19 or 3A4.
Other antidepressants
Other antidepressants have not been as well studied with regard to cardiac effects. In a randomized double-blind crossover study of 10 patients with impaired left ventricular ejection fraction taking imipramine or bupropion, bupropion had no significant cardiac effects (
171). In a study of 36 inpatients with cardiac disease, bupropion caused an increase in supine blood pressure, although it did not cause significant orthostatic hypotension, conduction disturbances, or ventricular arrhythmias. Bupropion did cause an exacerbation of baseline hypertension in two patients (
186). Venlafaxine has not been specifically studied in cardiac patients, but it may cause a dose-dependent increase in diastolic blood pressure starting at 150 mg/day, with significant increases at doses of 300 mg/day or above (
187). A 1-week randomized controlled trial of 20 patients—10 taking mirtazapine and 10 taking imipramine—found that mirtazapine caused a significant increase in heart rate and decrease in heart rate variability and had no effect on blood pressure or blood pressure variability (
188).
Nefazodone is rarely used in cardiac patients because of multiple drug interactions. One small open-label study in CHF patients showed that it was effective in treating major depression, with a significant reduction in heart rate and no changes in heart rate variability. The QT interval was increased, which is consistent with a reduced heart rate, but the QTc interval did not change (
189).
Monoamine oxidase inhibitors are almost never used in cardiac patients because of drug interactions, orthostatic hypotension, and the risk of hypertensive crises.
A number of SSRIs inhibit cytochrome P450 pathways, which has an impact on treatment decisions. Fluoxetine, paroxetine, and duloxetine inhibit 2D6. Nefazodone, fluoxetine, and, to a lesser extent, sertraline, are 3A4 inhibitors. Other medications, such as ketoconazole and erythromycin, are potent 3A4 inhibitors. Amiodarone and quinidine are 2D6 inhibitors and can elevate blood levels of fluoxetine, risperidone, and several tricyclics.
Tables 1, 2, and 3 summarize interactions between psychotropic, cardioactive, and cardiovascular drugs.
Antipsychotics
Antipsychotic medications may be used in small doses for short periods to treat delirium in cardiac patients who are in acute cardiac care settings or inpatient units. Longer-term and higher-dose therapy may be needed for cardiac patients who have a chronic psychotic disorder. The two situations are distinct, and some thought must be given to both the short-term and long-term risks and benefits of the various antipsychotic medications.
A number of antipsychotics have been linked to torsade de pointes and sudden death, among them pimozide, sertindole, droperidol, haloperidol, and thioridazine (
190). The greatest risk is associated with thioridazine. In a large retrospective case-control study of all sudden deaths in psychiatric wards of five hospitals in England over 11 years, the only antipsychotic that was found to be an independent risk factor for sudden death was thioridazine (
191). Of six major antipsychotics (thioridazine, ziprasidone, quetiapine, risperidone, olanzapine, and haloperidol), thioridazine produces the largest QTc prolongation, with a mean change of 35.6 ms (
190,
192,
193). Several excellent reviews have examined the relationship of antipsychotics to QTc prolongation (
191,
193–
198).
Among the atypical antipsychotics, none has been linked to torsade de pointes, even though most have a larger impact on QTc than haloperidol, which has been linked to torsade de pointes. Risperidone has been linked to one fatality due to pulseless electrical activity, and it has been reported to cause QTc and QRS prolongation in two cases of overdose and in 8 of 380 patients in a double-blind study by the manufacturer (
199). The fatality may have been due to factors other than QTc prolongation (
198). In two reported cases of ziprasidone overdose, neither patient developed torsade de pointes, though one had QRS prolongation and the other had QTc prolongation (
198). Aripiprazole, olanzapine, and quetiapine have not been linked to torsade de pointes.
In considering the use of drugs that may prolong the QT interval, factors to be reviewed include a family or personal history of long QT syndrome, a history of sudden cardiac arrest, syncope or unexplained seizure, arrhythmias, hypertension, valvular heart disease, bradycardia, and use of other medications that may prolong the QT interval or interfere with the metabolism of QT-prolonging agents. Class IA and class III antiarrhythmic drugs, dolasetron, droperidol, tacrolimus, levomethadyl acetate, other antipsychotic agents, many antibiotics (the “floxacins”), and antifungal agents may increase the risk of torsade. Magnesium and potassium levels should be monitored, as abnormalities may also increase the vulnerability to developing torsade (
190,
200,
201).
In addition to the potential proarrhythmic effects of the antipsychotics, the decision of which medication to select for patients with cardiac disease should take into account the drug’s potential to cause orthostatic hypotension, glucose intolerance, and hyperlipidemia. Orthostatic hypotension, which is related to the α1-adrenergic receptor blocking properties of antipsychotics, is seen most frequently with low-potency antipsychotics, such as chlorpromazine. Some atypical antipsychotics may also cause orthostatic hypotension. Hyperlipidemia, glucose intolerance, and diabetes mellitus, with or without weight gain, have been linked to most atypical antipsychotics, including clozapine, olanzapine, quetiapine, and risperidone. According to their manufacturers, aripiprazole and ziprasidone are less likely to cause these effects. In the initial phase of treatment, and periodically thereafter, blood sugar and lipid levels should be monitored.
Mood stabilizers
At therapeutic doses, lithium can cause sinus node dysfunction that is generally reversible when the medication is discontinued, although there have been rare reports of sinus arrest, atrioventricular block, and aggravation of ventricular arrhythmias (
207–
209). Lithium toxicity can cause sinoatrial block, atrioventricular block or dissociation, bradyarrhythmias, and ventricular tachycardia or fibrillation (
208). Generally, lithium can be used safely in cardiac patients even with reduced cardiac output by decreasing the dosage; the dosage can be decreased even further in patients with impaired renal function in advanced heart failure. Greater caution is necessary for patients taking diuretics, particularly thiazides, and those on salt-restricted diets. Lithium may also increase the risk of cardiac arrhythmias in patients taking angiotensin-converting enzyme inhibitors (
194). In patients with acute congestive heart failure exacerbations or acute coronary syndromes, the use of lithium should generally be avoided because of rapid electrolyte and fluid balance shifts.
Valproate and lamotrigine have no apparent cardiovascular effects. Carbamazepine has a tricyclic-like class IA antiarrhythmic effect and should be used only with cautions similar to those discussed above. It also induces cytochrome P450 enzyme 3A4, which can increase the metabolism of a number of anticoagulant and cardiovascular medications.