More accurate testing may be needed to diagnose heart attacks, after new research showed that two-thirds are missed by regular checks.
The study, presented today at the Cardiovascular Magnetic Resonance conference in Barcelona, followed 935 community-dwelling participants in Iceland, aged between 67 and 93 years.
A review of the patients at the beginning of the study found that 10% had had recognised heart attacks, while 17% were labelled as having unrecognised attacks, which were missed in routine medical checks but identified by an electrocardiogram or cardiovascular magnetic resonance (CMR) imaging.
This meant that a total of 63% of the heart attack patients were missed by regular clinical checks.
The patients – who were recruited between 2003-2007 – to monitor incidence of heart attack, heart failure and death by any cause. These results were analysed to assess the relationship between unrecognised heart attacks at the start with future cardiovascular events and death.
After five years, the mortality rate for those who had experienced unrecognised heart attacks had reached 13%, compared with 8% for those who had not experienced an attack, although recognised heart attacks still held the highest position at 19%.
At the 10 year mark however, recognised and unrecognised mortality rates had reached similar levels, at 51% and 49% respectively, showing a significant difference with those who had not experienced any attacks, which was at 30%.
The average age of the participants in the study was 76, with 52% being female, although the results were adjusted to account for age, sex and diabetes.
Lead author of the study Dr Tushar Acharya said: ‘63% (156 out of 247) of the myocardial infarctions identified by CMR were missed in routine medical care. Unrecognised MI may be more common than recognised MI’.
He then stressed the importance of identifying unrecognised heart attacks, as those who go undiagnosed ‘do not receive medications commonly prescribed to heart attack patients to reduce the risks of death or another heart attack.’
Such medications include aspirin, high intensity statins, angiotensin converting enzyme inhibitors and beta blockers. He also suggested that they should also be advised to control risk factors such as hypertension and diabetes.
Dr Acharya added, ‘Using CMR in patients with cardiac symptoms would likely detect many more heart attacks than traditional diagnostic tests. There are good therapies to treat survivors of MI so finding them early should improve prognoses.’
The paper concluded that while population screening to identify heart attacks using CMR is not cost-effective or practical, starting to shift a proportion of patients from traditional tests to CMR imaging could help to decrease the number of undiagnosed heart attack sufferers, allowing them to receive the appropriate treatment and implement lifestyle changes.