Revascularisation and ventricular restoration
Inadequate myocardial perfusion can cause impaired contractility; this can be either fixed (infarction) or reversible (hibernation). Coronary revascularisation in heart failure aims to improve myocardial function by reversing perfusion deficits to hibernating myocardium. Patients with heart failure of ischaemic aetiology can be assessed for myocardial viability by dobutamine stress echocardiography or thallium scintigraphy. Revascularisation of hibernating myocardium can reduce left ventricular volumes and improve left ventricular function (figures 9a and 9b).
Until publication of the STICH (Surgical Treatment for Ischaemic Heart Failure) trial results in 2011, the practice of revascularising hibernating myocardium was common but based on largely anecdotal evidence.
The HEART (Heart Failure Revascularisation Trial) study (n=138, average age 65 years, two-thirds of whom were NYHA I-II, median wall motion index 0.8 [equivalent to left ventricular ejection fraction (LVEF) of 24%]) was a randomised trial of OMT vs. OMT plus angiography with the intent to revascularise either via percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). Unlike STICH, the presence of myocardial viability was an inclusion criterion and the majority of patients did not have recent angina symptoms. However, like STICH, there was no difference in mortality between the OMT group and the revascularisation group. The study was closed early due to slow recruitment, sponsor withdrawal and the start of the STICH study – the results are underpowered as a result.12
The STICH trial (n=1212, median age 59 years, NYHA I-IV, median LVEF 27% in the treatment arm) found no significant difference in all-cause mortality rates between patients treated by revascularisation with coronary artery bypass grafting (CABG) plus optimal medical therapy (OMT) and those treated with OMT alone (figure 10).13
The results were controversial, at least in part because many investigators and researchers thought that they “knew” the result already: the anecdote in clinical medicine is very powerful. Many excuses were advanced for the neutral result:
- the majority of patients complained of angina rather than dyspnoea
- myocardial viability testing, while central to the studied hypothesis, was not an inclusion criterion
- on later core lab analysis, many patients were found to have LVEF >35%
- patients with left main stem disease are prime candidates for revascularisation but were excluded.
There matters rested until the STICH extension (STICHES) was published in 2016.14 The original patient cohort from STICH was followed for almost 10 years, and at that point, there was a small, but definite, survival advantage for the surgically treated group.
It’s important to note that the patients in STICH had a mean age just short of 60 and that it took a very long time for the survival advantage to appear. There is thus a reasonable argument that selected younger patients with heart failure (in whom angina is not a prominent problem) should be offered coronary angiography with a view to surgical revascularisation.
There is no evidence in favour of percutaneous coronary intervention (PCI) for heart failure. PCI might be thought to be safer than CABG, but complete coronary revascularisation is likely to be complex and involve attempts at opening chronic total occlusions. The REVIVED-BCIS2 (Efficacy and Safety of Percutaneous Coronary Intervention to Improve Survival in Heart Failure) study is currently recruiting patients for a randomised controlled trial of PCI plus OMT vs. OMT alone in patients with heart failure – myocardial viability is an inclusion criterion and the primary outcome is a composite of all-cause mortality or heart failure hospitalisation (NCT01920048).15