Managing Stable Coronary Disease: will the initial strategy
The preferred contemporary approach to the management of ‘stable ischemic heart disease‘(SIHD) or (chronic coronary syndrome) is not well defined.
Two strategies are commonly used.
- Conservative strategy uses guideline-based medical therapy, including (a) antianginal drugs as well as disease-modifying agents, such as (b) hypolipidemic, (c) antithrombotic, and (d) renin-angiotensin blocking therapies.
- Invasive strategy adds (a) coronary angiography, followed by either (b) percutaneous coronary intervention or (c) coronary-artery bypass grafting – CABG, to guideline-based medical therapy.
Important advances have occurred in both strategies, leading to equipoise as to which approach is preferable for patients with SIHD.
This report is on ‘International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA)’. This study reported whether an initial invasive strategy would result in better outcomes than a conservative strategy among patients with SIHD and moderate or severe myocardial ischemia.
In the main trial, 5179 patients underwent randomization at 320 centers in 37 countries. Another 777 patients who had advanced chronic kidney disease in addition to the other conditions were included in a separate trial (ISCHEMIA-CKD). Both trials used a patient-centric approach by incorporating sophisticated analyses of angina related quality of life.
Two arms of the study
- More patients underwent randomisation in each trial than in previous trials addressing this issue.
- Majority of patients also underwent coronary computed tomographic angiography at screening to confirm the presence of coronary obstruction and to rule out left main coronary artery disease.
- Unlike in previous trials, randomization to the conservative and invasive strategies in these trials was carried out before coronary angiography was performed, thereby reducing the likelihood of bias.
- 96% of the patients in the invasive-strategy group underwent coronary angiography, whereas only 26% of the patients in the conservative-strategy group did so, for an ischemic event or inadequate control of symptoms
There was no significant difference between the two strategies in the rate of death from cardiovascular causes, myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest (the primary end point in ISCHEMIA).
- The most straight forward conclusion is that, insofar as “hard” end points are concerned, the two strategies seem to be equally efficacious.
- When myocardial infarction was analyzed according to a secondary definition the number and pattern of myocardial infarctions differed, leading to results that favored the conservative strategy.
- Provided there is strict adherence to guideline-based medical therapy, patients with SIHD who fit the profile of those in ISCHEMIA and do not have unacceptable levels of angina can be treated with an initial conservative strategy. 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.
In addition there was another arm of the trial which focused on SIHD with advanced Chronic Kidney Disease. Among patients with SIHD who have advanced chronic kidney disease, the risk of clinical events is more than three times as high as the risk among those without chronic kidney disease. However an initial invasive strategy does not appear to reduce event rates or relieve angina symptoms for these patients. Therefore, patients with stable ischemic heart disease and chronic kidney disease can usually be treated with a conservative strategy.
The findings do not apply to patients with acute coronary syndromes, clinically significant left main coronary artery disease, low ejection fraction, class III or IV heart failure, or those who are very symptomatic despite the use of medical therapy at maximum acceptable doses.
Watch a 2 minute video explaining the results