Looking for insight: unexplained heart scarring after sudden cardiac arrest
I’m hoping someone in this community may have experienced something similar or can point us in the right direction.
My husband is in his early 40s and recently suffered a sudden cardiac arrest while exercising at the gym. He was active, energetic, not overweight, and had no idea that he had a serious heart problem before this happened.
Thankfully, he survived and now has an ICD/pacemaker for protection.
One finding from the day of his cardiac arrest that has always stood out to me is that when he arrived at the ER, his potassium was extremely low at 2.6 mmol/L. It was later corrected. We still don’t fully understand what role, if any, that severe hypokalemia may have played in triggering the cardiac arrest, especially in combination with the heart scar that was later discovered.
His cardiac workup showed no significant coronary blockage, so his doctors do not believe this was a typical heart attack.
His heart function was initially reduced after the arrest, with an ejection fraction around 35–40%, and it subsequently improved.
Cardiac MRI findings
His cardiac MRI is what concerns me the most. It showed an extensive non-ischemic pattern of myocardial fibrosis/scarring.
The scar was described as subepicardial/mid-wall late gadolinium enhancement (LGE), with a near-complete ring-like pattern, particularly involving the basal lateral and inferior walls and extending toward the septum.
His MRI estimated the scar burden at approximately 20%.
His LV and RV were normal in size, with an MRI LVEF around 47% and RVEF around 51%.
We were told that this scar could provide the electrical substrate that caused his dangerous arrhythmia/cardiac arrest.
The question we cannot seem to answer is:
Why does a relatively young, active person have this much heart scarring in the first place?
Genetic testing
Because the MRI pattern raised concern for a possible genetic cardiomyopathy, he underwent extensive genetic testing.
His testing included a large Invitae genetic panel with sequencing and deletion/duplication analysis of 163 genes, including many genes associated with cardiomyopathy and arrhythmias, such as DSP, FLNC, DSC2, DSG2, PKP2, LMNA, TTN, MYH7, SCN5A, RYR2, PLN, RBM20, DES and many others.
The overall result was NEGATIVE — no pathogenic or likely pathogenic genetic variants were identified that currently explain his condition.
So at this point, despite the extensive scar seen on MRI, we still do not have a confirmed genetic explanation.
Initially, different possibilities were discussed with us, including whether this could have resulted from a previous viral infection/myocarditis or an inflammatory process. The possibility of a relationship to a previous COVID infection or COVID vaccination was also raised, but nothing has been established as the cause.
We have essentially been told to continue his heart medications, allow the ICD to monitor/protect him, repeat imaging over time, and see whether the scarring progresses.
I completely understand the importance of monitoring, but after surviving a sudden cardiac arrest and finding this amount of unexplained heart scar, I’m not comfortable simply waiting without trying harder to understand the underlying cause.
I would love to hear from anyone who has dealt with a similar combination:
Sudden cardiac arrest during exercise
Potassium of 2.6 mmol/L at presentation
No significant coronary blockage
Subepicardial/mid-wall myocardial fibrosis
Near-complete ring-like/circumferential LGE pattern
Approximately 20% scar burden
Reduced EF that subsequently improved
Extensive genetic testing that was negative
No definite explanation for the myocardial scarring
Were you eventually given a diagnosis?
Did your doctors investigate previous myocarditis, cardiac sarcoidosis or another inflammatory condition, arrhythmogenic cardiomyopathy, autoimmune disease, previous viral infection, or another cause of non-ischemic myocardial fibrosis?
I’m particularly interested in whether anyone with a similar MRI pattern was evaluated with additional testing such as a cardiac FDG-PET scan, repeat cardiac MRI, inflammatory/autoimmune testing, additional genetic evaluation, or evaluation at a specialized inherited cardiomyopathy/arrhythmia center.
I’m also very interested in understanding the potassium finding. Could potassium as low as 2.6 have been an important trigger for the cardiac arrest in someone who already had this myocardial scar, even if the low potassium itself did not cause the scarring? And what could cause potassium to fall that low in an otherwise active person?
We are pursuing another medical opinion. I’m not looking for an internet diagnosis—I’m trying to educate myself so we can advocate for a thorough evaluation and make sure we’re not overlooking something important.
If you’ve experienced anything similar, or you’re a medical professional familiar with this type of cardiac MRI/scar pattern, I would be extremely grateful for any insight about what this pattern ultimately turned out to be, what additional testing helped, and what type of specialist we should consider seeing next.
Thank you so much. ❤️