Hello Dianaamirova,
Thank you for using Apple Support Communities. Specific watchOS features are not available in all regions. To view which watchOS features are available in your region, please review this link here: watchOS - Feature Availability - Apple
Review the section under "Health: ECG" to see which countries do support this feature. We also recommend that you review Apple's Unsolicited Idea Submission Policy. Specifically, the section under "Product Feedback". That way you can leave Apple feedback on things they change or improve: Legal - Unsolicited Idea Submission Policy - Apple
Thank you for using Apple Support Communities. Take care.