How to manage heart issues after chemo sessions at 47?

Question

Hello doctor,

I am a 47-year-old female who underwent six consecutive rounds of radiation (two years back with low-dose chemotherapy) and therapeutic chemotherapy for brain cancer last year, and stopped it this year due to complications. Last month, I experienced a four-hour SVT episode during treatment, triggered by a low potassium level (2.9) and a small caffeine intake. I was nearly cardioverted but self-stabilized and was able to tolerate 40 mEq of PO potassium with no repeat laboratory test.

Since then, I have had intermittent cardiac symptoms. Last week, I developed frequent PVCs and was again found to have a potassium of 2.9, no N/V or diarrhea. I was presented with a BP of 161/111 and a pulse of 117 to 130. After oral and IV replacement, I had a significant rebound of 5.1 within three hours. Three days back, I returned to the ED with continuous PVCs (8-30/min) lasting eight hours. Potassium at that time was 3.9. My magnesium and sodium were also stable, as was my cardiac panel, INR, and D-dimer.

Today, after having only one-fourth of a cup of coffee, I experienced flushing, anxiety, and a BP of 140/110. I took 1 milligram of Ativan, and my BP dropped to 101/85 with persistently elevated diastolic pressure and occasional PVCs. It is currently 107/91. Pulses are stable, and PVCs are present at five to seven per minute. I just started Propranolol 10 mg BID last night (I am currently tolerating five milligrams twice daily) and take 360 milligrams of magnesium daily.

It is also important to mention that I lost my only child 18 months ago and began cancer treatment six months later. The profound emotional trauma and cumulative stress may be contributing to autonomic dysregulation and cardiac reactivity. I have been referred to a cardiologist, but it may take some time to be seen.

Current medications and supplements I am taking are:

Propranolol 5 to 10 milligrams two times daily (newly prescribed for PVCs).
Keppra 1500 milligrams two times daily for seizure control.
Clobazam 20 milligrams at HS for seizure control.
Trazodone 125 milligrams at HS for sleep.
Ativan (Lorazepam) 1 milligram PRN is used rarely.
Ozempic 0.5 milligrams weekly for weight management (I gained 30 lbs during chemotherapy). I started off the year and lost 30.
Magnesium bisglycinate 360 milligrams daily.
Omega-3 daily (0.14 ounces).
Vitamin D 1000 IU daily with K2 160 µg.
Melatonin 10 milligrams at HS.
Creatine 0.18 ounces daily.
Vaginal estrogen cream is applied thinly to the affected area.

I am active and otherwise have no other past medical history.

My most important questions are:

Given this history and cardiac variability, how concerned should I be?
Could these episodes be due to autonomic dysregulation or a latent arrhythmia?
Are small potassium or caffeine shifts enough to trigger this in a sensitized system?
Should I be requesting additional investigations beyond Holter monitoring?
Is beta-blocker therapy appropriate for now, or should another agent be considered?

Please help.

Answer 1

Hello,

Welcome to iCliniq.com.

I understand your concern.

This is a complex situation that requires proper investigation and a multidisciplinary approach to diagnose the cause and treat it effectively. Many factors can contribute to premature ventricular contraction (PVC), supraventricular tachycardia (SVT), or any type of fast heart rhythm (Tachycardia).

From the history you have provided, it is evident that you do not always experience these arrhythmias with low potassium. For example, you had an arrhythmia even when your potassium level was 3.9, which is within the normal range. Also, potassium levels, especially when between 3.0 and 5.5, usually do not cause arrhythmias unless there are specific contributing factors.

There appear to be some contributing factors to your condition, including, as you rightly mentioned, small amounts of caffeine, stress, and possibly the use of Anticonvulsants or Antiepileptics (medicines used to control seizures). These medications are known to cause arrhythmias through various mechanisms, including electrolyte imbalance, trace element imbalance, and electrocardiogram (ECG) abnormalities that may trigger such events.

Another important point to mention is your history of chemotherapy. Many Chemotherapy Agents are well known to cause arrhythmias through different mechanisms, including cardiomyopathy. To investigate this further, an Echocardiogram is advised, and if necessary, your cardiologist may recommend a cardiac magnetic resonance imaging (MRI) scan for detailed evaluation.

It is also important to note that Semaglutide can contribute to premature ventricular contractions (PVCs) in several ways. However, since you are not experiencing nausea, vomiting, or diarrhea, this seems less likely in your case. Blood pressure fluctuations during episodes of tachycardia are common, and if your blood pressure remains normal otherwise, these changes should simply be monitored.

I would suggest the following measures:

Consult your cardiologist and undergo a Holter Monitor test and an echocardiogram, and if required, a cardiac MRI.
Continue your beta-blocker (Propranolol), as it is very effective in controlling premature ventricular contractions (PVCs) and supraventricular tachycardia (SVT). Once the underlying cause is identified, treatment can be tailored accordingly.
Consult your physician regarding the possible role of Semaglutide, Antiepileptics, or Anticonvulsants in your condition, and discuss alternative options if needed.
A Nephrology review may be considered later if electrolyte imbalances persist and all cardiac evaluations are normal, although this is not required at the moment.

Maintain good hydration and nutrition. Practice stress management and relaxation techniques to reduce anxiety. Autonomic dysregulation is a diagnosis of exclusion and should only be considered if all other investigations are normal.

I hope this information is helpful.

Please feel free to reach out again if you have further queries.

Thank you.

Answer 2

Hello,

Welcome back to icliniq.com.

I am truly glad to hear that my response was helpful to you, and I appreciate the update on the steps you have taken. It is great to know that you have connected with the appropriate specialists and are implementing the lifestyle and hydration strategies we discussed.

Please do not hesitate to reach out if new symptoms arise, if there is anything you are uncertain about, or simply if you need reassurance. I am here to support you in any way I can. Wishing you good health and a swift recovery.

I hope this has helped you.

Please feel free to reach out to me again if you have further queries.

Thank you.