AV nodal reentrant tachycardia (AVNRT) is not considered a life-threatening condition for the vast majority of people who have it. Episodes can feel alarming, with heart rates jumping to 120 to 280 beats per minute, but the arrhythmia originates within the AV node itself, not from damaged heart tissue. It is the most common type of supraventricular tachycardia, accounting for about 56% of cases, and it affects women roughly twice as often as men.
That said, “not dangerous” doesn’t mean “harmless.” While the immediate risk during any single episode is very low, there are real complications that can develop over time if AVNRT goes untreated, and certain groups face higher risks than others.
What Happens During an Episode
Your heart has two electrical routes leading into the AV node: a fast pathway and a slow pathway. Normally, signals travel down the fast pathway. In AVNRT, a premature heartbeat arrives when the fast pathway hasn’t recovered yet, so the signal detours down the slow pathway instead. By the time it reaches the bottom, the fast pathway has recovered, and the signal loops back up through it, creating a self-sustaining electrical circuit. The heart keeps firing in this loop, producing a sudden, rapid heartbeat.
More than 80% of AVNRT cases follow this “slow-fast” pattern. The rapid heart rate typically starts and stops abruptly, which is one of the hallmarks that distinguishes it from other causes of a fast pulse like anxiety or dehydration, where heart rate ramps up and down gradually.
Symptoms and When They Become Concerning
Most people experience palpitations, a fluttering or pounding sensation in the chest or neck. Dizziness, shortness of breath, and chest discomfort are common during episodes. Some people feel anxious or lightheaded. These symptoms are uncomfortable but not inherently dangerous in someone with an otherwise healthy heart.
Fainting during AVNRT is rare. Research shows that syncope from AVNRT almost always occurs alongside another condition, such as structural heart disease or advanced age, that further compromises the heart’s ability to pump effectively at high rates. In younger, otherwise healthy people, passing out from AVNRT alone is uncommon. Older adults are more vulnerable because they’re more likely to have underlying cardiac issues and because the heart tolerates rapid rates less well with age.
Long-Term Risks of Untreated AVNRT
The more serious concern with AVNRT isn’t any single episode. It’s what happens when frequent, prolonged episodes go untreated over months or years. A large study published in the Journal of the American Heart Association found that AVNRT treated with catheter ablation was still associated with increased rates of cardiomyopathy (weakening of the heart muscle), heart failure, and, among younger patients specifically, an increased rate of death compared to the general population. Even after accounting for subsequent treatment, these associations held.
This pattern is known as tachycardia-induced cardiomyopathy. When the heart races frequently for extended periods, the muscle can gradually weaken. The good news is that this type of cardiomyopathy is often reversible once the arrhythmia is controlled. But it underscores why people with frequent or prolonged episodes shouldn’t simply write off the condition as benign and ignore it.
Who Faces Higher Risk
AVNRT affects a wide age range, from children to people in their 90s, with an average age of about 45 at diagnosis. Women make up roughly 70% of AVNRT cases. In men, AVNRT becomes the dominant type of supraventricular tachycardia around age 40, while in women it takes over as early as age 10.
The condition poses greater risk for people who also have structural heart problems, such as valve disease, a thickened heart wall, or reduced pumping function. In these individuals, the rapid heart rate can drop blood pressure more significantly and lead to fainting or, rarely, more serious complications. People with frequent, long-lasting episodes (especially those lasting hours) are also at higher risk for the gradual heart muscle weakening described above.
Stopping an Episode at Home
Many AVNRT episodes can be terminated with vagal maneuvers, physical techniques that stimulate the vagus nerve and temporarily slow electrical conduction through the AV node. The most well-known is the Valsalva maneuver: bearing down as if straining during a bowel movement for about 15 seconds.
A modified version of this technique, where you blow hard into a syringe or similar resistance while sitting upright and then immediately lie flat with your legs raised, is significantly more effective. A meta-analysis found the modified Valsalva converted the rhythm about 43% of the time, compared to 17% for the standard technique. That’s roughly twice the success rate with a single attempt. Splashing cold water on your face or briefly immersing your face in ice water can also work by triggering the dive reflex.
If vagal maneuvers fail and the episode continues, emergency departments can administer a short-acting medication through an IV that typically stops the episode within seconds.
Catheter Ablation as a Permanent Fix
For people with recurrent episodes, catheter ablation is the definitive treatment. A thin wire is guided through a blood vessel to the heart, where targeted energy destroys the slow pathway responsible for the reentry circuit. Current guidelines from the European Society of Cardiology recommend offering ablation as an initial treatment choice for patients with recurrent AVNRT, rather than relying on long-term medication.
The procedure’s track record is excellent. In one study spanning 14 years and over 500 patients, the overall success rate was 99.6%, with a complication rate of 2.9%. The most serious potential complication is damage to the normal conduction system, which would require a permanent pacemaker, but this occurred in only 0.25% of cases. A separate multicenter analysis of over 10,000 supraventricular tachycardia ablations found an in-hospital mortality rate of just 0.02%, and neither death was attributed to the ablation procedure itself.
Other complications include cardiac tamponade (fluid collecting around the heart from a perforation), which occurred in about 0.26% of cases in the large multicenter study, and vascular injuries at the catheter insertion site requiring surgical repair, at a rate of about 0.1%. These are rare but real risks to weigh against the benefit of eliminating the arrhythmia permanently.
Medication for Ongoing Management
For people who prefer not to have ablation or who experience infrequent episodes, daily medications can reduce how often episodes occur. Calcium channel blockers, beta-blockers, and similar drugs that slow conduction through the AV node are the standard options. However, current guidelines have downgraded these from first-line to second-tier recommendations, reflecting the high success rate and low risk of ablation. Medications don’t cure the condition; they reduce episode frequency and heart rate during episodes, and they come with their own side effects like fatigue, low blood pressure, and dizziness.
Some people with very infrequent, well-tolerated episodes choose no treatment at all, relying on vagal maneuvers when episodes occur. This is a reasonable approach as long as episodes are short, infrequent, and don’t cause fainting or significant symptoms.