Smoking status and blood glucose levels are risk factors for having upper gastrointestinal bleeding (UGIB) after a heart attack, research shows.

Using data from a national Swedish medical registry, researchers found of almost 150,000 patients who had a heart attack between 2007 and 2016 approximately 1.5% suffered UGIB within a year of the event.

UGIB was linked to a poor prognosis, with an increased risk of death and stroke, they noted.

‘These novel insights substantiate data from previous studies showing that UGIB is a common and feared complication with substantial consequences in terms of morbidity, mortality, and medical care costs,’ the study authors wrote in the European Heart Journal – Cardiovascular Pharmacotherapy this week (23 August).

Using traditional statistical modelling together with machine learning methods, their analysis confirmed several known risk factors for UGIB including low levels of haemoglobin and age, as well as new risk factors including smoking and blood glucose.

‘The most important predictors… were haemoglobin, age, systolic blood pressure, blood glucose, previous UGIB, smoking status, antithrombotic treatment and gastroprotective treatment,’ wrote the authors who will present the findings at the European Society of Cardiology Congress this week.

Smoking had long been established as an ischaemic risk factor but had not previously been considered to increase bleeding risk, they noted, suggesting that infection with Helicobacter Pylori bacterium in the upper GI tract could be involved.

‘A common link could be an active, concomitant H. pylori infection that in combination with antithrombotic therapy substantially increases the risk of UGIB and is proposed to be associated with smoking,’ they wrote.

Meanwhile glucose levels could be ‘a proxy for the degree of stress that, in turn, could influence UGIB incidence’.

Lead author Moa Simonsson, deputy consultant at Sweden’s Karolinska University Hospital, said if high-risk patients were identified then clinicians could offer preventative therapies to reduce their risk of bleeding.

‘There are, for instance, drugs that combat bleeding complications, gut bacteria tests that can be used on risk groups and other possibilities for personalised treatment for heart attack patients at high risk of bleeding complications,’ she said in a statement.

Karolinska Instituet researchers are planning to research the significance of H. pylori infection in heart attack patients later this year, with a randomised trial investigating whether screening for and treating the common bacterial gut infection can reduce bleeding complications and improve prognosis after heart attack.

A pilot study last year showed a two-fold increase in the presence of H. pylori among heart attack patients.