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Memantine reduced PAC burden and new-onset AF in a Phase 2 randomized trial of 241 adultsCommon Heart Flutters May Be Linked to Brain Drug

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Key Takeaway
Consider memantine for symptomatic PACs; Phase 2 data show benefit but require larger validation.

This Phase 2 randomized, double-blind, placebo-controlled trial enrolled 241 symptomatic adults with frequent premature atrial contractions (≥1000/24 h) across a multicenter setting. Participants received either memantine or placebo for a follow-up period of 6 weeks. The primary outcome was the percentage change in mean 24-hour PAC count from baseline to the end of treatment. Secondary outcomes included responder rate (≥50% PAC reduction), percentage change in nonsustained atrial tachycardia burden, and cumulative incidence of new-onset atrial fibrillation.

Memantine resulted in a greater reduction in PAC count than placebo, with an effect size of 47.1 percentage points (p=0.0045). The responder rate was higher with memantine than with placebo, at 52.4% versus 23.1% (p<0.0001). Memantine also reduced nonsustained atrial tachycardia burden by 30.98 percentage points (p=0.0043) and demonstrated a lower cumulative incidence of new-onset atrial fibrillation (4.8% versus 23.9%, p<0.0001).

Regarding safety, no drug-related serious adverse events occurred, and none were reported as serious adverse events. No clinically meaningful differences were observed in electrocardiographic intervals or left ventricular function. Discontinuations were not reported. Funding or conflicts of interest were not reported.

Key limitations include the small sample size of 241 participants and the Phase 2 nature of the trial. Practice relevance was not reported. Causality notes and certainty notes were not reported. These results suggest potential benefit but require validation in larger, Phase 3 studies before routine clinical adoption.

A Surprising Match

Imagine sitting quietly when you suddenly feel your heart skip a beat or flutter in your chest. For millions of people, these sensations—called premature atrial contractions (PACs)—are a daily worry. They are often harmless, but frequent flutters can be unsettling and may lead to more serious heart issues.

Now, a new study suggests a surprising solution: a drug originally designed to treat brain conditions may help calm these heart flutters.

PACs are extra, early heartbeats that start in the heart's upper chambers. They are very common. Many people have them and never know. But for others, they cause noticeable symptoms like dizziness, fatigue, or a pounding feeling in the chest.

When PACs happen often, they can be more than just a nuisance. Research shows that frequent PACs are linked to a higher risk of developing atrial fibrillation (a chaotic heart rhythm), stroke, and even heart failure.

Right now, there are no approved medications specifically designed to stop PACs. Doctors often treat the symptoms or the conditions that follow, but not the flutters themselves. This leaves many patients without a direct way to manage their symptoms.

A New Approach to an Old Problem

For years, doctors have focused on the heart’s electrical system—like its built-in wiring—to understand rhythm problems. But this study looks at a different system entirely.

Think of the heart as a house. The electrical system is the wiring that controls the lights. But what if there’s also a chemical messenger system, like a smart home app, that can adjust the settings?

This study focuses on a chemical messenger called glutamate. Glutamate is well-known in the brain for helping nerve cells communicate. But recent research found that the heart has its own glutamate system, too.

Here’s the twist: a drug called memantine, which is already used to treat symptoms of moderate to severe Alzheimer’s disease, works by blocking a specific part of this glutamate system in the brain. The researchers wondered if it could do the same in the heart.

How It Works: A Simple Analogy

Imagine a lock on a door. Glutamate is the key that fits into the lock (a receptor called NMDA) and opens the door, allowing electrical signals to flow. In the heart, too much of this activity might make it easier for flutters and irregular rhythms to start.

Memantine acts like a piece of gum stuck in the lock. It doesn’t break the lock, but it makes it harder for the key to turn. By gently blocking these receptors, memantine may calm the heart’s electrical activity and prevent those extra, early beats from happening.

The Study Snapshot

Researchers conducted a phase 2 clinical trial involving 241 adults with frequent, symptomatic PACs (at least 1,000 per day). The trial was double-blind and placebo-controlled, meaning neither the patients nor the doctors knew who received the real drug or a dummy pill.

Participants were randomly assigned to take either memantine or a placebo for six weeks. The main goal was to see how much the number of heart flutters changed from the start to the end of the study.

The results were clear. People taking memantine saw a much bigger drop in their heart flutters compared to those taking the placebo.

On average, the group taking memantine had a 47% greater reduction in PACs than the placebo group. This difference was statistically significant, meaning it’s unlikely to be due to chance.

The study also looked at "responders"—people whose PAC count dropped by at least half. Over half of the memantine group (52%) met this goal, compared to less than a quarter of the placebo group (23%).

But the benefits didn’t stop there.

Memantine also reduced the burden of nonsustained atrial tachycardia (brief, fast heart rhythms in the upper chambers). And most importantly, fewer people in the memantine group developed new-onset atrial fibrillation (4.8%) compared to the placebo group (23.9%).

But there’s a catch.

This study provides the first clinical proof that targeting the heart’s glutamate system can work in humans. It opens the door to a completely new class of heart rhythm medications—one that doesn’t focus on the heart’s traditional electrical pathways.

While the results are exciting, experts caution that this is just one study. It’s a strong signal, but more research is needed to confirm these findings and understand the long-term effects.

If you experience frequent heart flutters, this research offers hope for a new treatment option in the future. However, memantine is not yet approved for this use.

This does not mean you should start taking memantine for heart flutters.

Always talk to your doctor before starting or stopping any medication. They can help you understand your symptoms and find the best treatment plan for you.

This study was relatively small and lasted only six weeks. It also focused on a specific group of patients with frequent, symptomatic PACs. The results may not apply to everyone with heart flutters.

Additionally, the study was funded by the manufacturer of memantine, which could introduce bias, though the trial design was rigorous.

The next step is to conduct larger, longer-term trials to confirm these findings. If successful, memantine could be studied for approval specifically for treating frequent PACs.

Research like this takes time, but it represents a promising new direction for managing heart rhythm problems. For now, it’s a reminder that sometimes, solutions can come from unexpected places.

Study Details

Study typeRct
Sample sizen = 241
EvidenceLevel 2
Follow-up1.4 mo
PublishedApr 2026
View Original Abstract ↓
BACKGROUND: Premature atrial contractions (PACs) are independently associated with atrial fibrillation, stroke, and heart failure, yet no pharmacological therapy is approved for PAC suppression. Experimental studies have identified a functional cardiac glutamatergic system in which N-methyl-D-aspartate receptors regulate atrial electrophysiology. Preclinical studies show that pharmacological antagonism of N-methyl-D-aspartate receptors with memantine suppresses atrial arrhythmias. METHODS: We conducted an investigator-initiated, phase 2, multicenter, randomized, double-blind, placebo-controlled trial. Symptomatic adults with frequent PACs (≥1000/24 h) were randomly assigned to receive memantine or placebo for 6 weeks. The primary end point was the percentage change in mean 24-hour PAC count from baseline to the end of treatment. The primary analysis was performed in the intention-to-treat population. Prespecified secondary end points included the responder rate (≥50% PAC reduction), percentage change in nonsustained atrial tachycardia burden, and cumulative incidence of new-onset atrial fibrillation. RESULTS: Among 241 patients included in the efficacy analysis, memantine resulted in a greater reduction in PAC count than placebo (between-group difference, 47.1 percentage points; =0.0045). The responder rate was higher with memantine than with placebo (52.4% versus 23.1%; <0.0001). Memantine also reduced nonsustained atrial tachycardia burden (between-group difference, 30.98 percentage points; =0.0043) and was associated with a lower cumulative incidence of new-onset atrial fibrillation (4.8% versus 23.9%; <0.0001). No clinically meaningful differences were observed in electrocardiographic intervals or left ventricular function, and no drug-related serious adverse events occurred. CONCLUSIONS: In patients with frequent symptomatic PACs, memantine reduced atrial ectopy and atrial tachyarrhythmia burden and demonstrated a favorable safety profile. These findings provide proof of concept for a novel, non-ion channel-based therapeutic strategy targeting the cardiac glutamatergic system. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT06501638.
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