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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
The modest benefits of a routine “angiography first” or “invasive” strategy for patients with some types of chest pain may come at the risk of increased bleeding.
The timing of “invasive” diagnosis and treatments, which include coronary artery catheter investigation and treatment with a stent, is an important part of care for people with heart attacks. In this review, the patients enrolled in eight underlying studies, all had unstable angina or a type of heart attack called non-ST elevation myocardial infarction (NSTEMI).
The routine “invasive” strategy offered early diagnosis and treatment of the narrowed arteries using coronary catheterisation and stents or bypass grafts if required. It was compared to a “selective” or “conservative” strategy. In this alternative approach, routine drug treatment was offered first and coronary angiography plus stent treatment later if symptoms or tests suggested it was needed.
There was no appreciable difference in deaths from all causes or non-fatal heart attack overall when the routine invasive group compared to conservative group. However the risk of a heart attack during the procedure was almost double, and the risk of bleeding as a complication of the catheterisation or treatment was also increased.
The cost and resource implications associated with having angiography and stenting available for everyone was not assessed in this review. There are potential system benefits to consider too, such as the lower readmission rates that were observed in the routine invasive group.
Taking into account a wider range of evidence, clinicians will be able to give more precise estimates of the potential harms and benefits to patients based on this review and an assessment of their risk.
Why was this study needed?
Both unstable angina (worsening chest pain) and NSTEMI carry a significant risk of recurrent heart attack and death. In 2013/14, there were 45,910 admissions for NSTEMI in England.
In the conservatively strategy arm, the risk of further heart attack was assessed using tools such as the Global Registry of Acute Cardiac Events (GRACE) or other tools. The invasive approach involved routine angiography and revascularisation in most or all patients who have no contraindications, irrespective of the risk score. The researchers wanted to look at all studies that had compared the benefits and harms of these strategies.
New trials have emerged since a 2010 review was published on the same topic. This update was needed to determine if these new trials changed the evidence- base and might warrant a change in guidance and practice.
What did this study do?
This updated Cochrane systematic reviewed eight randomised controlled trials published before August 2015. Five trials were included from an original 2010 review along with three new trials. All trials were carried out in the era in which stents were being used.
The review included 8,915 adults with either an episode of unstable angina, increasing level of resting pain, or tests indicating heart muscle damage without ST elevation on the ECG.
Half of the participants received a conservative management approach whilst the other half received the routine invasive approach.
There were differences in the trials in the time between randomisation and coronary angiography in the routine invasive group, between an average of six hours and four days. Participants varied per study, with some only including people over the age of 65.
What did it find?
At six to 12 months follow up the following events occurred.
- There was no difference in death from any cause at six to 12 months, with 36 deaths per 1,000 people in the routine invasive approach compared to 42 deaths per 1,000 people for the conservative approach (RR 0.87, 95% CI 0.64 to 1.18).
- The routine invasive strategy did not appreciably reduce the risk of myocardial infarction at six to 12 months, with 62 episodes per 1,000 people versus 78 per 1,000 people in the conservative strategy (relative risk [RR] 0.79, 95% confidence interval [CI] 0.63 to 1.00) technically a non-significant difference.
- There were fewer re-hospitalisations with the invasive strategy, 220 per 1,000 people versus 286 per 1,000 people in the conservative strategy (RR 0.77, 95% CI 0.63 to 0.94).
- The routine invasive strategy increased the risk of bleeding as a complication of investigation or treatment, 42 per 1,000 invasive versus 72 per 1,000 (RR 1.73, 95% CI 1.30 to 2.31) and procedure-related myocardial infarction, at 30 per 1,000 conservative versus 57 per 1,000 in the invasive approach (RR 1.87, 95% CI 1.47 to 2.37).
What does current guidance say on this issue?
NICE’s 2013 guidance on early management of unstable angina and NSTEMI provides recommendations for conservative management and early invasive management. It recommends conservative management without early coronary angiography for patients with a low risk of adverse cardiovascular events (a predicted six-month death of less than 3.0% on GRACE).
The early invasive approach of coronary angiography is recommended within 96 hours of hospital admission for people who have a moderate to high risk of adverse cardiovascular events (a predicted six-month death above 3.0%) and no contraindications. This strategy is also recommended for people initially assessed as at low risk of adverse cardiovascular events if there is ongoing chest pain or evidence of cardiac ischaemia demonstrated on exercise stress testing.
What are the implications?
When looking at a follow up of six to 12 months, this Cochrane review provides evidence that in people with unstable angina and NSTEMI the choice of approach is finely balanced. The authors suggest that the benefits may be more meaningful in a higher risk group and routine invasive approach may be the preferred management strategy for this group.
It is possible that recent changes in therapies or techniques at the time or angioplasty might further reduce the risk of bleeding and tip the balance in favour of invasive treatments for lower risk patients. Careful risk-based patient selection and discussion of possible harms will remain important.
There are resource implications to changing practice including increased availability of angiography and cardiac interventions out of hours. From a system perspective this added cost might be offset by a reduced re-hospitalisation rate.
Citation and Funding
Fanning JP, Nyong J, Scott IA, et al. Routine invasive strategies versus selective invasive strategies for unstable angina and non-ST elevation myocardial infarction in the stent era. Cochrane Database Syst Rev. 2016;(5):CD004815.
This project was funded by The Prince Charles Hospital Foundation, Australia, The University of Queensland Australia and The Cardiac Society of Australia and New Zealand.
Bibliography
NICE. Unstable angina and NSTEMI: early management. CG94. London. National Institute of Health and Care Excellence; 2013.
MINAP. Myocardial Ischaemia National Audit Project How the NHS cares for patients with heart attack. Annual Public Report April 2013-2014. London: Myocardial Ischaemia National Audit Project; 2014.
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