Here are five other afflictions that are more likely to strike you down cold before you can even blink—and what to do to survive them.
Instant killer: Hypertrophic cardiomyopathy
About one in 500 people have some form of this heart disorder, which causes the walls of your heart muscle to thicken and lose their pumping power. Approximately 1 percent of people with the disorder die suddenly each year, usually because of a too-rapid heartbeat—and many of them are young and unaware they even have heart issues.
In fact, hypertrophic cardiomyopathy is the most common cause of sudden cardiac death in people younger than 30. If you hear of an athlete falling dead on the field, this condition often takes the blame.
Survive it: Most cases of hypertrophic cardiomyopathy are genetic, says Jil Tardiff, M.D., Ph.D., of the University of Arizona College of Medicine.
Sit down with mom, dad, and grandma and ask if anyone in your family died young, of any cause. Many deaths that appear accidental—drowning, single-car wrecks, falls off a horse or motorcycle—actually occur when people with undetected cardiomyopathy go into sudden cardiac arrest, Dr. Tardiff says.
If you do have a suspicious family history, your doctor will probably recommend tests like an electrocardiogram and ultrasound. Plus, you should stay extra alert for warning signs, such as unusual shortness of breath, fainting, and fluttering heartbeats you haven’t had before.
People diagnosed with hypertrophic cardiomyopathy can work with a cardiologist to manage it—and avoid sudden death.
Medications, defibrillators, and sometimes surgery can help. And you’ll want to follow a carefully tailored exercise program. Sure, you might have to skip out on some sports that involve contact or start-and-stop action, like football, but you don’t want to be a couch potato with a heart condition, Dr. Tardiff says.
Instant killer: Faulty heart wiring
While cardiomyopathy changes your ticker’s shape and structure, another group of heart issues affects the electrical system that controls and synchronizes its beats, Dr. Wydro says. Rare but serious conditions such as Brugada syndrome, long QT syndrome, and Wolff-Parkinson-White syndrome scramble the signals that direct your heart to beat normally.
You might not have any signs until your heart’s lower chambers, the ventricles, start quivering instead of pumping properly—and you keel over.
Survive it: Genetics play a big role here, too, so climb your family tree with your doctor. Tests such as electrocardiograms and exercise stress tests can identify these conditions.
Like hypertrophic cardiomyopathy, you can work with a specialist to manage them using medications, pacemakers, and frequent follow-up visits, among other treatments.
The typical heart-healthy lifestyle can reduce the risk of sudden death even in people with these predispositions, Dr. Wydro says. Don’t smoke, and cut back on your boozing, since alcohol increases your likelihood of abnormal heart rhythms.
And tell your M.D. if you have bad dreams—nightmares and nighttime thrashing sometimes signal Brugada syndrome, which often kills people in their sleep.
Instant killer: Brain aneurysm
About 3 to 5 million Americans have one of these abnormal bulges in the wall of a brain blood vessel, according to the American Stroke Association.
Most linger silently, causing no symptoms. But according to a recent study in the journal Stroke, about one third of the aneurysms eventually rupture—an event that proves fatal about 40 percent of the time.
Survive it: Don’t blow off a sudden, severe headache—especially if it goes hand in hand with strange symptoms like a droopy eyelid, double vision, or a single dilated pupil. That might signal the aneurysm pressing against nerves in your brain.
Early detection is key: If doctors find an aneurysm before it bursts open, they can repair it with surgery or other treatments.
Step up your vigilance if your doc says your blood pressure is on the high side, Dr. Wydro says. The harder your blood pushes against an aneurysm, the greater the chance it ruptures.
Instant killer: Aortic dissection
In 2003, this condition struck down actor John Ritter, tearing a hole in the wall of the major artery leaving his heart.
Doctors aren’t sure exactly what causes these rips, but they can trigger blood to flow where it shouldn’t—or even a complete rupture of the aorta, which typically proves fatal. Aortic dissection occurs in only about two in every 10,000 people, but most are men ages 40 to 70, notes the National Institutes of Health.
Survive it: Sudden and excruciating pain in your chest or back serves as the main sign of aortic dissection, so get medical help if you experience it.
Before that, know your risk: It’s higher if you had a family member with the condition or if you have a connective tissue disorder like Ehlers-Danlos syndrome, which causes stretchy skin and super-flexible joints.
These diseases result in fragile blood vessels that rip more easily, Dr. Wydro says, so people who have them should seek medical attention for any unexplained chest or back pain (not just the most severe).
And, oddly, make sure you get a flu shot. According to research presented last year at the American Heart Association’s Scientific Sessions, hospital admissions for aortic dissections spike in peak flu season, perhaps because an inflammatory reaction to the virus triggers a tear in susceptible people.
Instant killer: Pulmonary embolism
Half of people with these blood clots in their lungs have no symptoms at all. But for 100,000 Americans per year, the clots block blood flow, jack up blood pressure in the lungs, and work the heart so hard it can’t keep up.
In fact, sudden death serves as the first symptom of a pulmonary embolism about a quarter of the time.
Survive it: Watch out for signs of blood clots elsewhere in your body, such as your legs and arms, Dr. Wydro says.
Treating them with blood-thinning medication can prevent them from breaking loose and traveling to your lungs.
Red flags include pain and swelling in one arm or leg that doesn’t go away within a day or two, especially if you’ve recently broken a bone, taken a long flight, or otherwise spent time not moving around very much.