context: It's not surprising if your doctor tells you that you have atrial fibrillation ( AFib) and heart failure at the same time. The two conditions are closely tied to each other. You need your heart to do one job and do it really well: pump blood throughout your body. For that, it needs a regular rhythm and strong, healthy muscle. But if you have AFib, your heart's upper chambers -- the atria -- are out of sync. They don't have that nice steady rhythm. Instead, they might be quivering like Jell- O. With heart failure, the muscles of your heart are too weak to pump enough blood, so you don't get the oxygen you need. AFib can lead to heart failure, and heart failure puts you at greater risk for AFib. When you have both, which is common, symptoms tend to be worse than when you have just one or the other. When you have AFib, your heart typically beats faster than normal, even when you're just resting. And since the heart's doing more of quiver than a strong push, it ends up sending out only a fraction of the blood it normally would. It's like the difference between a bunch of short, frantic bursts on a bike pump versus long, steady strokes. AFib can also cause fluid buildup in your lungs. Your lungs fill your blood with oxygen before sending it back to your heart. So now, your heart doesn't get enough oxygen-rich blood from the lungs, and even if it does, it's beating too fast to do a good job of pumping it out. And a rapid heartbeat -- or just one that's never regular -- can damage the muscles of your heart. All of that sets the stage for heart failure. Even though your heart's working really hard -- too hard -- your body's still not getting the oxygen it needs. It works in the other direction, too. Your heart's rhythm is controlled by electrical signals. For those signals to work well, they need healthy heart tissue. But heart failure can actually stretch your atria and cause tissue in your heart to thicken and scar. Those changes throw off the electrical signals, and that messes up the heart's rhythm and can cause AFib. AFib and heart failure are both common on their own. But many people have both, and doctors aren't totally clear why. One reason may be that many of the same things raise your chances of having both conditions. Risks you can't control. Some things you just can't change, such as: Age. The older you are, the greater the chances you'll get AFib or heart failure. Most people who have both conditions are older adults. Genes. There's still a lot of research to be done here, but certain differences in your genes may affect how likely it is that you end up with heart failure or AFib. Gender. Men are more likely to have these conditions than women. Heart disease. Your odds for heart failure and AFib go up if you have other heart conditions, such as: Coronary artery disease, where plaque builds up in your heart's arteries and leads to less blood flow Cardiomyopathy, which is damage to your heart muscle Heart valve problems, such as a leaky valve or a valve that doesn't fully open Myocarditis, where the muscles of your heart get swollen and irritated Other health conditions. Other health issues can also raise your risk, such as: Diabetes, since it increases your odds for coronary artery disease and high blood pressure High blood pressure, which over time can weaken, stiffen, and thicken your heart tissue Obesity, as it often leads to higher blood pressure and raises your chances of having diabetes Overactive thyroid, because too much thyroid hormone can make your heart beat faster than normal Sleep apnea, which can lead to lower oxygen levels while you sleep and affect your heart's rhythm Smoking and drinking alcohol. Just on its own, smoking raises your odds for all kinds of heart disease, including AFib and heart failure. But it's even more dangerous if you have risks in play. Over time, heavy drinking weakens your heart's muscles. And for some people, alcohol acts as a trigger for AFib.