EKG monitoring for patients on antipsychotics

One of the controversies in pharmacologic management has been the need to monitor EKGs in patients who are on antipsychotic medication.  This was not much of an issue until Geodon was approved for treatment of schizophrenia a number of years ago.  During the initial studies, it was noticed that there was an increased risk of a certain type of EKG change.  With its expansion into use in Bipolar Disorders, the number of prescriptions written for it has skyrocketed and, more than ever, we must contend with this issue.  So . . . what, really, is the issue???

Turns out that some medicines (Geodon being only one of them) can change the intervals in the lumps and bumps on an EKG. These lumps and bumps each correspond to the flow of electricity through the heart and, in turn, the contraction and relaxation of different parts of the heart.   Each of the squiggles on an EKG has been given a letter name and the safe and pathologic intervals between these are well established.  When a cardiologist reads your EKG, he or she is measuring these intervals and looking for specific patterns in the various electrical views of the heart taken in a standard EKG.  During the approval process for Geodon, it was noticed that there was an increased risk of “prolonged QTc”.  What is that and what does it mean?  If you think of an EKG in your mind, the most defining feature is the tall spike in the middle of the other squiggles.  That is called the QRS complex.  “R” being the point at the top of the wave, and “Q” and “S” being the bottom of the wave (left and right side respectively).  The QRS complex corresponds to the contraction of the ventricles of the heart–the big chambers that send blood to the lungs and to the rest of your body.  Right after the QRS complex is the “T” wave.  This is more gentle and sloping.  This represents the relaxation of the ventricles.  The distance between the “Q” and the end of the “T” can vary with heart rate.  If your rate is very high, then the QT is shorter.  To deal with that, cardiologists have come up with the “QTc” or the corrected QT-interval . . . corrected for the changes in the value caused by an increase in heart rate.   If the QTc is prolonged, it increases the risk of a lethal cardiac arrhythmia.  Anytime a medicine is used that can increase QTc, it is a reasonable precaution to check the EKG to make sure that QTc is not prolonged.  The assumption has always been that if you have an OK EKG on the medicine, you are good to go.  Or are you . . . ?

An article in the June, 2005 edition of the Journal of Clinical Psychopharmacology found that patterns of QTc prolongation are not necessarily consistent in patients receiving antipsychotic medicines.  When EKGs were administered over time to patients taking various doses of various antipsychotic medications, those who were positive for QTc prolongation were not consistently positive for QTc prolongation.  While the study was small and did not include rigorous measurement of blood levels of the medicine, it did call into question the value of a single EKG for clearance for patients taking a medicine that can prolonge QT intervals.  It was recommended that an additional EKG be taken to increase the chances of finding an abnormal value (if one exists).  This may be even more important in patients with other factors that can lead to QTc prolongation and arrhythmias (bradycardia–heart rates < 60, pre-existing heart disease, and some electrolyte abnormalities).

 So, should you be worried if you are on Geodon???


Should you have an EKG???

Yes . . . and probably a second . . . just to increase the margin of safety. 

–Dan Hartman, MD

2 comments to EKG monitoring for patients on antipsychotics

  • Mooserx

    Would you order an EKG on anyone who was about to start any medication that increases QTc intervals, and there are a lot, including some antibiotics? Baseline EKG is the only way to tell, since EKGs can be different from person to person. Maybe not for short term meds, but I think it would be great for antipsychotics, to catch it before anything else happens.

  • Moose–
    It depends on how ultraconservative you want to be as a doctor. Do we need to get baselines on everyone??? No. How do you know which people to order tests on??? Not sure. If someone is older, has a history of underlying cardiac issues, a family history of sudden unexplained death, etc., then it would be a good idea. The rate of “long QT syndrome” is very rare (I don’t know the exact number) so that across the board testing is not indicated. The intensity of the follow ups would depend on the medicine and on the underlying medical issues. As the study showed, the presence of the long QTc was inconsistent even on the same medicine. Getting two is reasonable. I think that much of the decision boils down to informed consent and asking the patient what they are comfortable with. Some are easily frightened by the potential medical side effects and may want more frequent testing. That is fine. At this point, I will not get routine baselines unless there is an indication to do so or a desire on the part of the patient. I will get two follow-ups on patients. More only if I have specific reasons to worry or if the patient desires it.

    –DH MD