The National Institutes of Health (NIH) recently published the results of studies based on a controversy that has remained unresolved for decades. The ISCHEMIA study is not only the largest (5000 patients) study of its kind but perhaps among the most significant. It appears in the March 30 issue of the New England Journal of Medicine.
About the ISCHEMIA Study
NHLB, a division of the National Institutes of Health, funded the ISCHEMIA Quality of Life study. Preliminary findings were released last year at the annual meeting of the American Heart Association.
The most recently published articles represent the official results of ISCHEMIA.
The study tracked patients with mild heart disease, as well as moderate to complex heart disease, for thirty-eight months. Heart disease affects eighteen million people in the U.S. and is the number one cause of death.
Conservative Treatment vs. Invasive Treatment
The strategy behind the conservative procedure is that it is a non-invasive approach. Patients in the study’s conservative arm were administered medications for the control of blood pressure, angina (narrowed coronary arteries), and cholesterol. Exercise and nutrition counseling was the main treatment for this group.
The invasive strategy also includes exercise and nutrition counseling. But if a patient’s stress test results are abnormal, invasive coronary procedures are performed as soon as possible.
Participants were included in the invasive study after a diagnosis of ischemic heart disease, an obstruction of arterial blood flow to the brain or heart.
Key Elements of the Study
The researchers set out to discover which procedure would be the most effective. They applied both strategies to patients experiencing heart failure, unstable angina, cardiac arrest that had been resuscitated, and heart failure. In addition, one of their goals was to study the patients’ quality of life.
From 2012 Through 2018
The ISCHEMIA study enrolled a total of 5,179 patients during the period of August 2012 through January 2018. The patients were an average of sixty-four years of age. The number of sites totaled 320 in thirty-seven countries.
The majority of patients in the study had exhibited chest pain on an average of once each day or each week. About thirty-five percent of participants had no chest pain during the month prior to enrollment.
By random selection, patients were chosen to receive conservative therapy unless symptoms become severe.
The second cohort received medical therapy only. These patients would be able to switch over to invasive procedures, if warranted, during or after a stress test.
During the trial period, twenty-one percent of patients participating in the conservative therapy group received bypass surgery or stent implants. The remaining patients completed the trial receiving medication as therapy.
Seventy-nine percent of the patients in the intervention group underwent revascularization. This surgical procedure, which includes coronary artery bypass, creates a new or additional blood supply. Seventy- five percent of the group undergoing surgical procedures received stents. The other patients had bypass surgery.
No Significant Difference in the Two Groups
The death rate between the conservative group and the invasive group was basically the same. One hundred forty-five patients died in the invasive procedure group. One hundred forty-four patients died in the group that received medication only.
Disease-related incidents were close in both groups. Three hundred fifty-two patients in the conservative group had heart attacks and other related issues during the study.
Three hundred eighteen patients in the invasive group experienced attacks.
Co-author Dr. Judith Hochman commented that they had been aware that stents and other surgical procedures present a risk of heart damage. The doctors reasoned, however, that the heart damage relating to invasive procedures was not as serious as spontaneous heart attacks.
The benefits of invasive procedures over conservative therapy remained consistent for about two-thirds of angina patients. The researchers found that for angina patients, it is safe to start treatment with medication and move to invasive therapy if symptoms continue.
There are two types of angina. Stable angina is chest discomfort or shortness of breath caused by stress or exertion.
Unstable angina is also chest discomfort or shortness of breath but it occurs for the first time for no specific reason. It is usually not associated with activities and can even occur while resting.
About the NHLBI and the NIH
The studies were funded by the National Heart, Lung, and Blood Institute (NHLBI) which is part of the National Institute of Health. The NHLBI conducts and supports research in lung, heart, and blood disorders.
In Conclusion
During a four-year follow-up, the ISCHEMIA study showed that in the long run, patients’ symptoms and quality of life improved using invasive strategies when. However, there was no benefit if the patient was not experiencing symptoms.
