Planning and Conducting the ISCHEMIA Trial

Noninvasive Coronary Atherosclerotic Plaque Imaging

Coronary artery disease is the leading cause of morbidity and mortality worldwide. Despite remarkable advances in the management of coronary artery disease, the prediction of adverse coronary events remains challenging. Over the preceding decades, considerable effort has been made to improve risk stratification using noninvasive imaging. Recently, these efforts have increasingly focused on the direct imaging of coronary atherosclerotic plaque. Modern imaging now allows imaging of coronary plaque burden, plaque type, atherosclerotic plaque activity, and plaque thrombosis, which have major potential to refine patient risk stratification, aid decision making, and advance future clinical practice.

Ischemia Trial: Does the Cardiology Community Need to Pivot or Continue Current Practices?

PURPOSE OF REVIEW

For decades, the standard of care for stable ischemic heart disease (SIHD) has been an ischemia-centric approach based on largely observational data suggesting a survival benefit of revascularization in patients with moderate-or-severe ischemia. In this article, we will objectively review the evolution of the ischemia paradigm, the trial evidence comparing revascularization to medical therapy in SIHD, and what contemporary practice should be in 2022.

RECENT FINDINGS

Randomized trials, including COURAGE and, most recently, the ISCHEMIA trial, have shown no reduction in "hard outcomes" like death and myocardial infarction (MI) in SIHD compared to medical therapy. The trial excluded high-risk patients with left main disease, low ejection fraction (EF) < 35%, and severe unacceptable angina. Irrespective of the severity of ischemia and the extent of coronary artery disease (CAD), revascularization did not offer any prognostic advantage over medical therapy. On the other hand, there was a durable improvement in symptoms. While there are many caveats to the ISCHEMIA trial, the overall strengths of the trial outweigh these limitations. The findings of ISCHEMIA are consistent with previous trials. It is time for the cardiology community to pivot towards medical therapy as the initial step for most patients with SIHD. Physicians should have the "COURAGE" to embrace "ISCHEMIA" and be comfortable with treating ischemia medically.

ISCHEMIA Trial: Key Questions and Answers

A healthy lifestyle, myocardial revascularisation and medical therapy constitute the three pillars for the treatment of ischaemic heart disease. Lifestyle and optimal medical therapy should be used in all cases. However, the selection of cases for revascularisation among stable patients remains controversial. The ISCHEMIA trial compared an early invasive strategy with revascularisation plus optimal medical therapy against initial optimal medical therapy alone with revascularisation reserved for cases in which symptom control was insufficient. The study included over 5,000 patients with stable coronary artery disease and moderate to severe myocardial ischaemia. No differences were found in relevant clinical outcomes, including all-cause mortality, cardiovascular death, MI, heart failure and stroke, over a follow-up of 3.2 years. Conversely, angina control was better in patients with severe symptomatic angina. Following the tradition of all trials comparing medical therapy alone with revascularisation, the ISCHEMIA trial results are controversial, but an analysis of the design and results of the trial offers important information to better understand, evaluate and treat the growing number of patients with stable chronic ischaemic heart disease and moderate to severe myocardial ischaemia.

Importance of Internal Variability in Clinical Trials of Cardiovascular Disease

A well conducted randomised controlled trial (RCT) is extremely important in the field of cardiovascular medicine. At the same time, it is equally important to understand the strengths and limitations of any RCT, and internal variability is a concept in clinical trials that is poorly understood. Variability in a clinical trial may be introduced at an individual level or during measurement, sampling, or conduct of the trial. It is not the same as internal validity, which is a broader concept of accuracy; to be valid, a study should minimise variability and have sound methodology. There are various steps that may be followed to minimise the internal variability in a clinical trial. One aspect of great importance is the adjudication process, which should be done meticulously and is often a step that is overlooked. It is important to standardise each step as much as possible, to ensure consistency and reduce noise at all levels. The concepts discussed in this review may serve as a roadmap to limit the influence of internal variability and maximise internal validity of RCT results.

Clinical Implications of the ISCHEMIA Trial: Invasive vs Conservative Approach in Stable Coronary Disease

PURPOSE OF REVIEW

To identify key strengths and weaknesses of the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial and explore its clinical implications in patients with stable ischemic heart disease.

RECENT FINDINGS

Previous studies have shown inconsistent benefit of early angiography and revascularization in patients with stable ischemic heart disease. The ISCHEMIA trial showed no significant reduction in mortality or cardiovascular outcomes in patients undergoing early angiography and revascularization with guideline-directed medical therapy compared to patients on medical therapy alone in specific patient population with stable coronary artery disease. The ISCHEMIA trial provides insights into invasive versus pharmacological treatment for patients with stable ischemic heart disease. Though it may have reduced applicability given its broad exclusion criteria, it offers useful information about the utility of non-invasive imaging modalities for selecting optimal revascularization candidates.

Coronary Revascularization and Long-Term Survivorship in Chronic Coronary Syndrome

Ischemic heart disease (IHD) persists as the leading cause of death in the Western world. In recent decades, great headway has been made in reducing mortality due to IHD, based around secondary prevention. The advent of coronary revascularization techniques, first coronary artery bypass grafting (CABG) surgery in the 1960s and then percutaneous coronary intervention (PCI) in the 1970s, has represented one of the major breakthroughs in medicine during the last century. The benefit provided by these techniques, especially PCI, has been crucial in lowering mortality rates in acute coronary syndrome (ACS). However, in the setting where IHD is most prevalent, namely chronic coronary syndrome (CCS), the increase in life expectancy provided by coronary revascularization is controversial. Over more than 40 years, several clinical trials have been carried out comparing optimal medical treatment (OMT) alone with a strategy of routine coronary revascularization on top of OMT. Beyond a certain degree of symptomatic improvement and lower incidence of minor events, routine invasive management has not demonstrated a convincing effect in terms of reducing mortality in CCS. Based on the accumulated evidence more than half a century after the first revascularization procedures were used, invasive management should be considered in those patients with uncontrolled symptoms despite OMT or high-risk features related to left ventricular function, coronary anatomy, or functional assessment, taking into account the patient expectations and preferences.

Coronary 18F-Sodium Fluoride Uptake Predicts Outcomes in Patients With Coronary Artery Disease

BACKGROUND

Reliable methods for predicting myocardial infarction in patients with established coronary artery disease are lacking. Coronary ¹⁸F-sodium fluoride (¹⁸F-NaF) positron emission tomography (PET) provides an assessment of atherosclerosis activity.

OBJECTIVES

This study assessed whether ¹⁸F-NaF PET predicts myocardial infarction and provides additional prognostic information to current methods of risk stratification.

METHODS

Patients with known coronary artery disease underwent ¹⁸F-NaF PET computed tomography and were followed up for fatal or nonfatal myocardial infarction over 42 months (interquartile range: 31 to 49 months). Total coronary ¹⁸F-NaF uptake was determined by the coronary microcalcification activity (CMA).

RESULTS

In a post hoc analysis of data collected for prospective observational studies, the authors studied 293 study participants (age: 65 ± 9 years; 84% men), of whom 203 (69%) showed increased coronary ¹⁸F-NaF activity (CMA >0). Fatal or nonfatal myocardial infarction occurred only in patients with increased coronary ¹⁸F-NaF activity (20 of 203 with a CMA >0 vs. 0 of 90 with a CMA of 0; p < 0.001). On receiver operator curve analysis, fatal or nonfatal myocardial infarction prediction was highest for ¹⁸F-NaF CMA, outperforming coronary calcium scoring, modified Duke coronary artery disease index and Reduction of Atherothrombosis for Continued Health (REACH) and Secondary Manifestations of Arterial Disease (SMART) risk scores (area under the curve: 0.76 vs. 0.54, 0.62, 0.52, and 0.54, respectively; p < 0.001 for all). Patients with CMA >1.56 had a >7-fold increase in fatal or nonfatal myocardial infarction (hazard ratio: 7.1; 95% confidence interval: 2.2 to 25.1; p = 0.003) independent of age, sex, risk factors, segment involvement and coronary calcium scores, presence of coronary stents, coronary stenosis, REACH and SMART scores, the Duke coronary artery disease index, and recent myocardial infarction.

CONCLUSIONS

In patients with established coronary artery disease, ¹⁸F-NaF PET provides powerful independent prediction of fatal or nonfatal myocardial infarction.

Initial Invasive or Conservative Strategy for Stable Coronary Disease

BACKGROUND

Among patients with stable coronary disease and moderate or severe ischemia, whether clinical outcomes are better in those who receive an invasive intervention plus medical therapy than in those who receive medical therapy alone is uncertain.

METHODS

We randomly assigned 5179 patients with moderate or severe ischemia to an initial invasive strategy (angiography and revascularization when feasible) and medical therapy or to an initial conservative strategy of medical therapy alone and angiography if medical therapy failed. The primary outcome was a composite of death from cardiovascular causes, myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. A key secondary outcome was death from cardiovascular causes or myocardial infarction.

RESULTS

Over a median of 3.2 years, 318 primary outcome events occurred in the invasive-strategy group and 352 occurred in the conservative-strategy group. At 6 months, the cumulative event rate was 5.3% in the invasive-strategy group and 3.4% in the conservative-strategy group (difference, 1.9 percentage points; 95% confidence interval [CI], 0.8 to 3.0); at 5 years, the cumulative event rate was 16.4% and 18.2%, respectively (difference, -1.8 percentage points; 95% CI, -4.7 to 1.0). Results were similar with respect to the key secondary outcome. The incidence of the primary outcome was sensitive to the definition of myocardial infarction; a secondary analysis yielded more procedural myocardial infarctions of uncertain clinical importance. There were 145 deaths in the invasive-strategy group and 144 deaths in the conservative-strategy group (hazard ratio, 1.05; 95% CI, 0.83 to 1.32).

CONCLUSIONS

Among patients with stable coronary disease and moderate or severe ischemia, we did not find evidence that an initial invasive strategy, as compared with an initial conservative strategy, reduced the risk of ischemic cardiovascular events or death from any cause over a median of 3.2 years. The trial findings were sensitive to the definition of myocardial infarction that was used. (Funded by the National Heart, Lung, and Blood Institute and others; ISCHEMIA ClinicalTrials.gov number, NCT01471522.).

Current approach to the diagnosis of atherosclerotic coronary artery disease: more questions than answers

Despite its commonality in routine clinical practice, the approach to a diagnosis of atherosclerotic coronary artery disease remains complex and, in part, contentious. The traditional dogma linking ischaemia to hard clinical outcomes has been questioned and reframed over the years; rather than being a predictor of hard clinical outcomes, the degree of ischaemia may simply be a marker of atherosclerotic disease burden. A renewed interest in the imaging of plaque burden has spawned the contemporary role of CT imaging for not only diagnosis and prognosis, but also for dictating downstream management. As the technology develops and evidence expands, decisions on investigative modalities remain centred around patient factors, local availability, test performance and cost. This review summarizes the available methods for diagnosis in the symptomatic patient and provides an overview of the current evidence behind functional and anatomical approaches.