Is an ECG from your smartwatch actually useful?
For detecting atrial fibrillation, a smartwatch ECG can be useful, especially as a supplement to medical monitoring. For other heart conditions, the evidence is still too thin.
For atrial fibrillation (AF), a heart rhythm disorder that can cause strokes, smartwatch ECGs have been well studied. A meta-analysis found a sensitivity of 93% and a specificity of 94%. That is impressive for a wristwatch1.
In practice, performance varies considerably. A study of 201 patients tested five brands, including the Apple Watch 6, Samsung Galaxy Watch 3, and Fitbit Sense. Sensitivity ranged from 58% to 85%, and in 17 to 26% of measurements the algorithm gave no result at all. When a doctor reviewed those borderline cases, 99% were still classified correctly. Without medical follow-up, such a watch is therefore a limited tool2.
In older adults after a stroke (mean age 79 years), the Fitbit Charge 5 automatically missed as many as 66% of AF cases. But when it did raise an alarm, that was almost always correct. A green notification can be taken seriously; no notification is not reassurance3.
A major advantage of a smartwatch is continuous monitoring. AF sometimes occurs in brief episodes that a one-off measurement at the GP's office misses. The Apple Heart Study and Fitbit Heart Study show that smartwatches detect such episodes more often4. For other heart problems, such as oxygen deficiency in the heart muscle, the watch ECG does not yet work well enough5,6.
If you want to track your heart rate variability, a measure of recovery and stress, via a Samsung smartwatch, do so at night. During the day, movement causes too many measurement errors. Nighttime measurements do agree well with a standard measurement7. And remember: a smartwatch signals, but does not replace a doctor or healthy lifestyle habits8.
Based on one meta-analysis (PMID 32921618), one prospective study of 201 patients (PMID 36858690), one validation study in stroke patients (PMID 37430546), two technical reviews (PMID 37562224, 33441002), one validation study with 28 participants (PMID 36480505), two large observational studies (Apple Heart Study and Fitbit Heart Study, summarised in PMID 39363440), and a review remark (PMID 35624593). The evidence for AF detection is strongest; for other applications it is thinner.
Is a calcium score of my heart worth doing?
For people aged 40 to 75 in a grey zone regarding statins, a calcium score is a well-supported tool for making a considered decision about medication together with your doctor.
Are calcium supplements bad for your heart?
Calcium supplements may be associated with an increased cardiac risk, but not all studies confirm this. It is preferable to obtain calcium from your diet, and discuss with your doctor whether a supplement is truly necessary for you.
Does climbing stairs actually do anything for my heart?
Yes, climbing stairs genuinely does something for your heart. Climbing roughly 50 to 100 steps a day is associated with fewer heart attacks, strokes and irregular heart rhythms, though this is based on observational studies, not experiments.
Is the Mediterranean diet really good for your heart, and why?
For people with an elevated cardiovascular risk, the Mediterranean diet is the best-supported dietary choice currently available. Both large trials and dozens of population studies confirm a lower risk of heart attack and stroke.
Is interval training (HIIT) better for my heart than regular cardio?
For cardiac patients in rehabilitation, HIIT produces greater fitness gains on average than regular cardio, but this does not apply to all heart conditions. If you have a heart problem, never simply start HIIT without medical advice first.
Does my heart rate variability (HRV) tell me anything about my health?
A higher HRV is associated with better health and greater resilience. Slow breathing is the most accessible and best-supported way to work on that yourself.