Atrial Fibrillation and Symptoms – A Great Mystery

A small study of patients before and after cardioversion opens our eyes to the complexity of how humans report symptoms.

One of the toughest problems in the care of patients with atrial fibrillation (AF) is sorting out symptoms. The tails are easy: some know the second AF starts and they feel awful; others feel nothing when in AF. The largest group of AF patients have some symptoms but whether it correlates with the heart rhythm (regular or not) is hard to know.

One of the most common ways we evaluate symptoms from AF is to cardiovert the patient. Cardioversion is a quick procedure where a patient gets a strong sedative and in the 5 minutes of sedation, we shock the heart back to regular rhythm. Then we assess whether the patient feels better in regular sinus rhythm (SR).

You may be thinking: of course, people feel better in regular sinus rhythm. And in many cases, they do. But sometimes sinus rhythm does not make them better. In these patients, it makes little sense to proceed with further procedures like ablation.

I call cardioversion both a diagnostic and therapeutic procedure.

A neat little study published in the journal Europace complicates this simple post-CV assessment. Wait till you hear the results.

This was a subanalysis of a study called the TeleConvert-AF study, which looked at whether a novel smartphone app used in patients with persistent AF scheduled for cardioversion could effectively detect spontaneous conversion to sinus rhythm or whether the persistent AF wasn’t actually persistent but intermittent.

That study found that the 3x-daily app recordings discovered that a few patients converted to SR on their own (14%) while another 5% of patients were noted to have intermittent AF (and it makes no sense to cardiovert them since they are cardioverting themselves).

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For the subanalysis patients used the smartphone app to record symptoms and heart rhythm 3x daily in the weeks before and after a cardioversion.

Here are the main findings:

• Baseline symptom burden was highly variable: median pre-ECV symptom load was 20.7% (range 0–100%).

• Overall symptom load dropped significantly after ECV (or cancellation due to spontaneous conversion) — from 20.7% to 7.2% (p<0.001).

• But the response was far from uniform: only about half of patients (50.4%) actually improved, 18.3% stayed stable, and nearly a third (30.2%) got worse.

• AF recurrence was the strongest predictor of no improvement.

• However…rhythm and symptoms didn’t track perfectly: among patients who stayed in sinus rhythm, only 68.5% felt better, while surprisingly 40.5% of patients whose AF recurred still reported improved symptoms.

Comments

These are interesting observations. It tells us that, yes, staying in SR matters but it isn’t anywhere near a strong correlation. Only 2/3rds of the patients who stayed in SR felt better while 40% of those who had AF recur still felt better—which could be placebo effect but also could be due to subtle changes in medications. (For instance, we often reduce rate-slowing medications after cardioversion.)

These are important and interesting observations. It shows how silly it is to simply think that all patients will feel better after SR and then poorly when AF comes back.

Since AF ablation is done almost exclusively to relieve symptoms, the massive variability in symptoms should induce a bit of humility in us.

We would be very cautious about ablating a person who feels better after cardioversion but is still in AF. We would also not be excited about doing ablation on a person who still feels bad while in SR. In these two patients, there is clearly a poor correlation between the heart rhythm and symptoms.

I wonder whether this or similar smartphone apps may turn out to be more than just a research tool. Perhaps in the future, it could be used to objectively measure the correlation between symptoms and rhythm.

Finally, not all medical studies have to be randomized trials. Here is a nice observational study describing things we see clinically but understand poorly.