Invasive approaches such as PCI and CABG offer no benefits over conservative medical therapy for patients with stable coronary disease who have moderate or severe ischaemia, according to the long-awaited results of the ISCHEMIA study.
Published in the NEJM, the findings from the study that enrolled more than 5000 patients showed no difference in the primary outcome, a composite of death from cardiovascular causes, myocardial infarction, or hospitalisation for unstable angina, heart failure, or resuscitated cardiac arrest between invasive or conservative approaches during an average of 3.2 years of follow up.
Similarly no differences between the two approaches were seen in a linked trial involving a group of 777 patients who also had advanced chronic kidney disease.
The invasive strategy was associated with fewer anginal symptoms than the conservative-strategy overall although the magnitude of this benefit depended on angina frequency at baseline, and 35% had no angina at baseline.
In the multicentre international study, which included centres in Australia, 5177 patients were randomised to either an initial invasive strategy of angiography and revascularisation when feasible in addition to medical therapy, or to an initial conservative strategy of medical therapy alone and angiography if medical therapy failed.
During early follow up there were more events in the invasive arm of the trial: 5.3% vs 3.4% in the conservative-strategy group. However over time the adverse outcomes were lower in the invasive group, so that at five years, the cumulative event rates were 16.4% and 18.2%, respectively.
Overall the primary outcome measure was seen in 318 patients in the invasive arm and 353 patients in the conservative arm of the trial, a difference which was not significant.
The study investigators noted that with most patients taking cardioprotective agents such as lipid lowering and antiplatelet drugs, the overall deaths rates were low, at around 6.4% in both groups at four years. They also noted that the findings were consistent regardless of how outcomes such as myocardial infarction were analysed.
“Thus, provided there is strict adherence to guideline-based medical therapy, patients with stable ischemic heart disease who fit the profile of those in ISCHEMIA and do not have unacceptable levels of angina can be treated with an initial conservative strategy,” an accompanying commentary concluded.
“However, an invasive strategy, which more effectively relieves symptoms of angina (especially in patients with frequent episodes), is a reasonable approach at any point in time for symptom relief.”
The ISCHEMIA study’s Australian national lead researcher, Professor Joseph Selvanayagam Professor of Cardiology at Flinders University, Adelaide, says the results show there is no need to rush patients with stable coronary disease and moderate-to-severe myocardial ischemia, to invasive coronary angiography.
“It’s a landmark study with a very important message for the number one health condition in Australia,” he said.
“It is perfectly safe to treat these patients with cholesterol lowering drugs, anti-platelet drugs and antianginal drugs, and then monitor their progress.”
“In most cases, patients in the medical therapy arm did perfectly fine and did not need to have invasive angiography and stenting/bypass.”
“We can reserve stents or bypass options for patients who struggle with unacceptable side-effects from medications, or who have bad angina despite maximal medical therapies – although even here we have to make it clear to patients they are taking operative options for symptom relief.”