The study by Duke University in North Carolina, states: "Based on the wider health literature, the expectation is that marriage - particularly a long, stable marriage - promotes social control and shared obligations that encourage the cessation/avoidance of smoking and excess alcohol consumption, regular medical check-ups, and other behaviours that are important for managing illness."
It is the latest academic paper to highlight the importance of marriage, which previous research has found protects couples from having heart attacks in the first place.
Nagging is a form of support, with a wife pestering her husband to take his heart pills showing that she cares. People who have never married are 73 per cent more likely to die following a heart attack than those in a continuous marriage, with this put down in part to a lack of social support.
The study, published in the journal Social Science and Medicine, looked at almost 2,200 people over the age of 50 who had suffered a heart attack during a major US study between 1992 and 2010.
The protection offered by long marriages is clear in that every 10 per cent rise in the number of years someone was married cut their risk of dying, from any cause, by 7 per cent.
Divorce is almost as bad for someone's post-heart attack survival as being unmarried, with divorcees 70 per cent more likely to die than if they had stayed married.
And the first eight years of a second marriage still hold a greater risk of death, mainly due to behaviour such as lack of exercise.
Maureen Talbot, of the British Heart Foundation, said: "Whether you're married, divorced or single, the main cause of a heart attack is the build-up of fatty plaque in your arteries. People are more likely to have a heart attack or stroke as they get older so it is important to determine any necessary lifestyle changes as early as possible to reduce your risk."