An important study to investigate the extent of heart attack (myocardial infarction) and its impact on left ventricular systolic function in SCAD patients was published on 3 January by the European Society of Cardiology European Heart Journal, the highest ranked cardiology journal globally.
Authors of the study include Dr David Adlam, who is leading the UK SCAD research, Dr Alice Wood, Research Fellow on the SCAD research project in Leicester, and Dr Abtehale Al-Hussaini, cardiology consultant who also worked on the SCAD research project.
158 SCAD patients from the UK SCAD Registry, and 59 healthy controls underwent CMR (cardiac magnetic resonance imaging) to look at their hearts and heart function.
- The patients were 98% female with an average age at the time of SCAD of 45.8 years
- 15 patients had a SCAD during or after pregnancy (P-SCAD)
- A third of SCAD patients had STEMI (ST-Elevation Myocardial Infarction), which are more serious than NSTEMI (Non- ST-Elevation Myocardial Infarction)
- 9% had had a cardiac arrest.
The study found that:
- The left anterior descending (LAD) artery was the most commonly affected (68.6%).
- Type 2 SCAD (a long diffuse and smooth narrowing mainly in the mid-to-distal) was the most common (72.9%).
- 56 patients were managed with PCI (percutaneous coronary intervention – ‘stenting’), of whom 25 had complications following the procedure.
- The most common complication was due to the haematoma (bruise) extending, and the rest were due to distal coronary or branch blockages resulting from stenting
- 8% of patients had emergency coronary artery bypass grafting, half after an initial attempt at PCI.
- SCAD patients in general had a very small reduction in ejection fraction (a measure of left ventricular systolic function), preserving cardiac function well in most cases.
- A large proportion of patients (39%) do not have a detectable heart attack and a minority (6.4%) had a very large one.
- P-SCAD was associated with larger heart attacks.
Key messages in this study include:
While a small number of SCAD survivors will be left with a larger heart scar, in most cases the lasting damage to the heart is small and in almost 40% of cases there is no detectable scar on MRI scanning after the heart has been allowed time to recover.
The paper also identifies the things associated with larger heart injuries which are:
- ST-elevation (a feature on the ECG) at any point after presentation
- Poor blood flow in the affected coronary artery
- Muti-vessel SCAD
- There is also a signal for P-SCAD with this likely due to P-SCAD causing more extensive dissections
Dr Adlam said the paper has important implications. Firstly, the fact that 40% of cases have no detectable scar suggests that for a significant number of SCAD survivors the requirement for medications usually given after heart attacks leading to heart damage (particularly the ACE-inhibitor (-pril) and ARB (-sartan) group may be less strong (unless these medications are needed for other reasons such as high blood pressure).
Secondly, while this study confirms previous findings of high complication rates with coronary intervention (including stenting), it also identifies the key features which determine heart injury after SCAD. Knowing these features is helpful as it may be that these are features that cardiologists can use to identify SCAD patients at higher risk and in whom coronary intervention is still the best strategy despite the inherent risks.
It needs to be noted that this is observational data not a clinical trial, but it is an important step forward in our understanding of the impact of SCAD on the heart and what factors cause larger heart injuries in SCAD.
Dr Adlam said: “We are hugely grateful to the SCAD survivors, healthy volunteers and heart attack survivors who gave their time to allow this research to be carried out. We are also grateful to our funders and particularly Beat SCAD for their support, without which we would not have been able to continue our research.”
Chair of Beat SCAD, Rebecca Breslin said: “This study is an important step forward in our understanding of SCAD. The fact that the majority of SCAD patients have no or small heart attacks and preserved ejection fractions is very positive. This, and the identification of factors that are more likely to lead to larger heart attacks, including multivessel SCAD hypermobility features, will help health professionals in their treatment and management of SCAD patients.”