Death after heart surgery is more prevalent among people living in deprived areas of England, according to data collected by five hospitals in Birmingham and the north west.
But this is not necessarily caused by bad diet, smoking or other aspects of an unhealthy lifestyle, according to a study published in the British Medical Journal (BMJ).
Say the authors: "Smoking, extremes of BMI and diabetes were strongly associated with social deprivation, but even after we adjusted for these factors, deprivation remained a predictor of reduced survival in hospital and at midterm."
The report is based on data gathered over ten years from 44,902 patients aged from 58 to 71, average 65. All had heart surgery between 1997 and 2007, and included current smokers (21%), ex-smokers (48%) never-smokers (30%) and diabetics (16%).
It shows that 1,461 (3.25%) died in hospital, and 5,563 (12.4%) in the first five years after surgery. Diabetes carried a 31% increase in risk, and smoking a 29% increase.
Dr Mike Knapton, associate medical director at the British Heart Foundation (BHF), said: "This study highlights the fact that it is not enough to provide heart patients with high-quality surgery, we also need excellent pre-operative care and cardiac rehabilitation to address inequalities in health.
"Cardiac rehabilitation is a lifesaving and cost-effective treatment, yet many patients still do not get access to it - a major piece of unfinished business."