Is an abnormal EKG with LBBB dangerous?

Submitted by Dr T on June 17, 2014 – 9:33am

Question:

I am a 78 yo male who has been a long distance runner for over 30 yrs. I have been healthy; 5’7,127 lbs. My blood pressure has been borderline hypertensive over the last year so I take the smallest dose of HCTZ and take 5mg of simvastatin (chol 178, Hdl 79). Last week I had severe dehydration due to food poisoning and went to urgent care after I passed out. They did an EKG which showed LBBB. The next day I went to my Dr who did another EKG, which was perfectly normal and gave me IV fluids to rehydrate me. He sent me for a cardio lite stress test and today I had that and when I first started on the treadmill my EKG was normal then as I progressed my EKG converted to LBBB. I have no symptoms and had resumed biking and running after I got over my GI upset without problem. I thought all was ok so should I be worried?

(from: Training for a Heart Attack)

A Left Bundle Branch Block (LBBB) that comes and goes when you are stressed may be suggestive of coronary artery disease.

As I suggested in this blog, your best way forward might be to ask for a CTCA. If the stress test and CTCA are both negative, you don’t have coronary artery disease and are safe, but I am a little worried that you might be especially at risk, since you are usually asymtomatic and thus don’t get warning signals to stop your activities if and/or when your heart doesn’t get enough blood, increasing your risk for a heart attack.

On the other hand, regular exercise and other heart -healthy lifestyle measures such as yours are the best protective measures aginst a heart attack you can take. Therefore it is all the more important you get these tests completed and know waht to do!

Hope this helps,
Dr T

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