“Obesity is more deadly than previously thought, with Australian research finding those with a BMI over 30kg/m2 have a 40% higher risk of sudden cardiac death than normal-weight people.
The risk is highest in those who are obese from a young age.
And most episodes of sudden cardiac death occur in patients with no other risk factors and seemingly normal hearts.
The systematic review and meta-analysis of 12 studies including 1.4 million people was presented this week at the European Society of Cardiology Congress in Barcelona.
The authors, both cardiologists from the University of Adelaide, said they were surprised by the findings, in particular, that epicardial fat actually infiltrated into the heart muscle.
“We thought it would be inactive,” said author Dr Rajiv Mahajan.
But he admitted the exact mechanisms at play were still unclear.
A high waist-to-height ratio was also a significant predictor of sudden death, he said.
The team made another surprising discovery.
Being underweight (with a BMI below 18.5kg/m2) was also fraught with more danger than expected, with the data showing it is associated with a 33% higher risk of sudden cardiac death.
Again, the mechanism is unknown but fragility is hypothesised.
Interestingly, Dr Mahajan said that overweight (25-29kg/m2) individuals were in the clear.
He said the results were strong: obesity and underweight are associated with sudden cardiac death, independently of comorbidities.
“I think before we call for new clinical practice guidelines we need more work on the mechanisms,” he said, adding that opportunistic screening in primary care could be shaped from that.”
Dr Sudheer S. Gudipalli