Heart attacks of course do happen, particularly to older and less healthy individuals but could sinister forces carry out an assassination make it look normal and it appear to only be a heart attack/Covid? The simple answer is yes and it was exposed in the 1970s.
At a testimony of the Church Committee before the US Congress in 1975, testimony revealed a secret CIA weapons program in which a heart attack was used to carry out assassinations. A small poison dart is shot at the person they are hoping to assassinate and all it leaves on the body is a small red dot. Furthermore as military.com reports, “The poisonous dart completely disintegrates upon entering the target. The lethal poison then rapidly enters the bloodstream causing a heart attack. Once the damage is done, the poison denatures quickly, so that an autopsy is very unlikely to detect that the heart attack resulted from anything other than natural causes.”