New analysis from the British Heart Foundation found that 90 per cent of coronary heart disease (CHD) patients have at least one other long-term illness.
There are around 2.3 million people living with CHD across the UK, and nine in ten suffer a so-called multi-morbidity including high blood pressure, diabetes or dementia.
The charity warned that the NHS is traditionally focused on treating individual illnesses as it called for a more personalised approach for people with more than one condition.
BHF’s analysis also found that 57 per cent of CHD patients suffer at least three other long-term conditions.
Over half of CHD patients (56 per cent) suffer from high blood pressure, 26 per cent have diabetes and 14 per cent have also suffered a stroke.
Around one in eight (13 per cent) also suffer heart failure and one in 20 (five per cent) also have dementia, BHF found.
The BHF said that previous research has shown that CHD patients are more than twice as likely to suffer a stroke, or develop vascular dementia.
The charity has called for more research to improve the understanding of how conditions like stroke and vascular dementia are connected and to develop new treatments for people living with multiple conditions.
Simon Gillespie, chief executive at the British Heart Foundation, said: “Over the years we’ve made huge progress in improving survival rates for single conditions like heart attacks with BHF-funded research leading the way.
“However, today’s figures point towards an emerging and very urgent challenge.
“For example, increasing numbers of people are surviving heart attacks, but are going on to suffer strokes or live with additional conditions like vascular dementia.
“These conditions limit people’s quality of life, increase their risk of dying and will place increasing pressure on the NHS and social care system across the UK.
“The NHS has traditionally focused on treating individual illnesses rather than individuals.
“We need a more personalised approach to be taken to the treatment of people living with multiple diseases.
“We can only reverse this trend by funding more research into all conditions of the heart and circulatory system, with a focus on how they can be treated together.”
Professor Sir Nilesh Samani, medical director at the British Heart Foundation, added: “More research is needed to understand the underlying reasons for the connections between different conditions, and why the number of people living with multiple diseases is rising at such speed.”