ISCHEMIA Trial: Findings & Conclusions
Written by Chris Balwanz, MD
Many of you may have heard about the ISCHEMIA trial results that were presented at AHA in November. This large, multi-center, randomized control trial has important implications on how we care for patients with STABLE ischemic heart disease (SIHD).
In addition, there was an associated study ISCHEMIA QoL that examined quality of life in these patients.
What is the ISCHEMIA trial?
The ISCHEMIA trial was designed to compare clinical outcomes with an initial invasive strategy versus a conservative treatment strategy for managing SIHD patients with moderate or severe ischemia on stress testing.
The study specifically aimed to determine if an initial invasive approach of cardiac catheterization with optimal revascularization (PCI or CABG) if feasible + optimal medical therapy (OMT) in patients with SIHD and moderate or severe ischemia would reduce:
- The primary composite endpoint of cardiovascular death
- Nonfatal MI
- Resuscitated cardiac arrest (RCA)
- Hospitalization for unstable angina (UA)
- Heart failure (HF)
Over an average follow-up of ~ 3.5 years. This was compared to initial conservative strategy of OMT alone with catheterization reserved for failure of OMT. Several secondary endpoints were also evaluated.
Who was involved in the ISCHEMIA trial?
The study enrolled 8,518 patients over the age of 18 with SIHD and at least moderate ischemia on stress testing. Of these, 5,179 patients were determined to be eligible based on additional screening and randomized at 320 sites.
Demographics of the study participants:
- Median age 64
- 23% women
- 34% non-white
- 41% diabetic
- 90% with a history of angina
75% of qualifying patients participated in stress imaging, and the rest did simple exercise treadmill stress tests. Among the 3,912 participants who underwent coronary computed tomography angiography (CCTA), 79% had multivessel CAD and 87% had left anterior descending (LAD) stenosis (proximal in 47%).
ISCHEMIA Trial Study - Inclusion and exclusion criteria (slide 12)
An initial invasive strategy as compared with an initial conservative strategy did not demonstrate a reduced risk for patients with SIHD and moderate to severe ischemia on stress testing over a median 3.3 years for a composite of CV death, MI, hospitalization for UA, HF, and RCA.
ISCHEMIA Trial Study - Summary (slide 28) The curves cross for the primary endpoint and the major secondary endpoint at approximately two years from randomization.
- Procedural MIs were increased with an invasive strategy.
- Spontaneous MIs were reduced with an invasive strategy.
- Surprisingly low all-cause mortality in both groups despite high-risk clinical characteristics, high-risk ischemia and extensive CAD.
- No heterogeneity of treatment effect, including by type of stress test, severity of ischemia or extent of CAD.
- Very low rates of procedure-related stroke and death.
The ISCHEMIA trial did have some limitations:
- Based on exclusion criteria, the trial results do not apply to patients with:
- Acute coronary syndromes within two months
- Highly symptomatic patients
- Left main stenosis
- LVEF <35%
- Trial results may not be generalizable to centers with higher procedural complication rates
- Completeness of revascularization has not yet been well studied
- Women were enrolled in the trial; however, they were more often excluded from randomization compared to men due to less ischemia and more non-obstructive CAD
- It was a non-blinded trial (no sham procedure)
ISCHEMIA Quality of Life Study
- Patients with SIHD and moderate-to-severe ischemia had significant and durable improvements in their angina and quality of life with an invasive strategy if they had angina (daily/weekly or monthly).
- In patients without angina, an invasive strategy led to minimal symptom or quality of life benefits compared to a conservative strategy.
Thus, in patients with SIHD and angina as well as moderate to severe ischemia on their stress testing, the decision to pursue an initial invasive vs conservative approach should align with patients’ goals and preferences.
Register for the Hearts & Huskers Spring Cardiology Conference
At Bryan Heart we put the patient first and tailor treatment plans to fit the patient’s individual needs. Our goal is to collaborate with you as the provider and the patient to set the best plan of care moving forward.
To learn more about the ISCHEMIA trial, join us at our 17th annual Hearts & Huskers Spring Cardiology Conference where Brock Cookman, DO, will speak directly to the study in further detail. We look forward to seeing you there!