A heart murmur itself is often harmless. Many people live with a soft murmur for years without ever knowing it, and for most, it’s a benign sound picked up during a routine exam. But there’s a difference between a murmur that’s stable and one that signals an underlying valve problem is progressing. When a murmur becomes serious, it usually sends quiet signals first. The challenge is that these signals can be easy to write off as aging, fatigue, or being out of shape.
If you have a known heart murmur—or if you’ve been told you have a leaky or tight valve—it helps to know which subtle changes deserve attention. Here are three quiet signs that a murmur may be becoming more significant, and what they mean for your heart health.
1. You’re Short of Breath with Routine Activities
This isn’t about being winded after sprinting up three flights of stairs. The change is more gradual. You might notice that tasks you used to do without thinking—carrying groceries from the car, walking across a parking lot, making the bed—now leave you a little breathless. You might find yourself pausing to catch your breath when you didn’t used to.
Why does this happen with a serious murmur? Your heart’s valves are supposed to open fully and close tightly. When a murmur is caused by stenosis (a narrowed valve that doesn’t open well) or regurgitation (a valve that doesn’t close well and leaks blood backward), the heart has to work harder to pump blood forward. Over time, pressure builds in the lungs, and fluid can start to collect there. That extra fluid makes it harder for oxygen to get into your blood, so you feel short of breath even with light effort.
Pay attention to the pattern. If you’re breathless when lying flat at night and feel better propped up on pillows, or if you wake up suddenly gasping for air, that’s a sign the heart is struggling to keep up with the fluid shift when you lie down. Both are worth mentioning to your doctor.
2. You Feel Unusually Tired or Lightheaded
Fatigue is easy to pin on a busy life, but the fatigue from a worsening heart murmur has a different quality. It’s deep—the kind of tired that makes you want to stop what you’re doing and sit down, even if you haven’t done much. You might feel unusually heavy or drained after a short walk or a few minutes of talking.
The mechanism here is similar. When your heart isn’t pumping blood efficiently, the brain and muscles receive less oxygen, so every task takes more energy. Some people also notice lightheadedness or dizziness when they stand up quickly, because blood pressure can drop when the heart can’t adjust fast enough to the change in position.
Dizziness that comes with chest discomfort, a fluttering feeling, or a noticeably fast or irregular heartbeat is more concerning. It could mean the valve problem is affecting your heart’s rhythm or that your blood pressure is swinging. If you feel faint or like you might pass out, that should be evaluated promptly.
3. You Notice Swelling in Your Ankles, Feet, or Abdomen
Swelling is a sign that fluid is backing up in your body. In the context of a heart murmur, it often means the heart isn’t pumping blood forward well enough, so blood backs up in the veins. Gravity pulls that extra fluid down into your lower legs and feet. You might notice your shoes feeling tight by the end of the day, or indentations in your skin after you take off your socks.
Swelling doesn’t always happen at once. It can be subtle at first—a slight puffiness around the ankles that comes and goes. Over weeks or months, it may become more persistent. In more advanced cases, swelling can move up into the belly, causing a feeling of bloating or a rapid increase in waist size. This happens when fluid collects in the abdominal cavity, a sign that the heart’s pumping ability has dropped significantly.
A simple check: press a finger gently on the swollen area for a few seconds, then lift it. If a dent remains, that’s called pitting edema, and it’s a clear sign of fluid retention. It doesn’t always mean the heart is failing, but it does mean you need an evaluation to find out why the fluid is accumulating.
When to Call Your Doctor
If you have a known heart murmur and you notice any of these three signs, it doesn’t necessarily mean an emergency. But it does mean it’s time to call your doctor and describe exactly what you’re feeling. They may want to listen to your heart again, order an echocardiogram to look at valve structure and function, or check for changes in your heart rhythm.
A worsening murmur can often be managed well if it’s caught early. Treatments range from medication to help the heart work more efficiently to valve repair or replacement when needed. The goal is to catch the progression before it causes lasting damage to the heart muscle or lungs.
What Doesn’t Usually Mean Danger
Not all changes are red flags. If you have a murmur and feel a little more out of breath after a night of poor sleep or a day of salty food, that may be temporary. Chest pain that is sharp and lasts only a second or two is rarely from the heart. Heart murmurs themselves don’t cause pain. If you have pain along with the signs above, it’s worth mentioning—but isolated, fleeting chest twinges are usually not from valve problems.
The quiet signs of a serious murmur build over time. By staying aware of how your body feels with everyday effort, you give yourself the best chance of noticing a change early. Your heart will tell you when it’s struggling; the trick is knowing what to listen for.
