Outcomes of Anatomical versus Functional Testing for Coronary Artery Disease

May Le, Mercer University College of Pharmacy 2015

According to the American Heart Association (AHA), coronary artery disease (CAD) is the cause for one in every five deaths in the developed world.  The AHA also states that about 16.8 million Americans are affected by this condition, leading to millions of people with myocardial infarction (MI)1.  Thus, timely diagnosis is critical to prevent mortality according to a review of 134 studies.  This review also states that symptoms suggestive of CAD, such as chronic stable angina, require further investigation for possible CAD.  Resting or exercising electrocardiography, invasive coronary angiography, and a noninvasive stress test are some diagnostic tools utilized in the investigation.2

A recent published study compared the use of computed tomographic angiography (CTA) versus functional testing in patients with symptoms suggestive of CAD.3

Title:  Outcomes of Anatomical versus Functional Testing for Coronary Artery Disease3
Design Randomized; 10,003 participants
Objective To compare health outcomes in patients who presented with new symptoms suggestive of CAD that required further evaluation and who were randomly assigned to an initial strategy of anatomical testing with the use of CTA or to functional testing
Study Groups CTA group (n= 4,996) versus functional testing group (n= 5,007)
Methods Symptomatic patients received either CTA (noninvasive anatomical testing) or functional testing (exercise electrocardiography, nuclear stress testing, or stress echocardiography).
Duration July 27, 2010 to October 31, 2014
Primary Outcome Measure Composite primary end point: death, myocardial infarction (MI), hospitalization for unstable angina, or major procedural complication
Baseline Characteristics CTA group: mean age 60.7, female 51.9%, ethnic minority 23.5%, mean body mass index (BMI) 30.5, hypertension 65%, diabetes 21.3%, dyslipidemia 67.4%, peripheral arterial or cerebrovascular disease 5.3%, metabolic syndrome 37.4%, current or past tobacco use 50.7%, chest pain symptom 73.6%, dyspnea on exertion (DOE) symptom 14.3%, other symptom 12.2%

Functional testing group: mean age 60.9, female 53.4%, ethnic minority 21.8%, mean body mass index (BMI) 30.5, hypertension 65%, diabetes 21.5%, dyslipidemia 67.9%, peripheral arterial or cerebrovascular disease 5.8%, metabolic syndrome 38%, current or past tobacco use 51.4%, chest pain symptom 71.9%, dyspnea on exertion (DOE) symptom 15.5%, other symptom 12.5%

Results Composite primary end-point event occurred: 164 of 4,996 patients in the CTA group (3.3%), 151 of 5,007 patients in the functional testing group (3%)

Adjusted hazard ratio 1.04, 95% confidence interval, 0.83 to 1.29; p= 0.75

Death: CT group 74, functional testing group 75

Nonfatal MI: CT group 30, functional testing group 40

Hospitalized for unstable angina: CT group 61, functional testing group 41

Major procedural complication: CT group 4, functional testing group 5

P value not provided

Adverse Events Common Adverse Events: not reported
Serious Adverse Events: not reported
Percentage that Discontinued due to Adverse Events: not reported
Study Author Conclusions In symptomatic patients with suspected CAD who required noninvasive testing, a strategy of initial CTA, as compared with functional testing, did not improve clinical outcomes over a median follow-up of two years.

This study shows that there is no statistically significant difference in clinical outcomes when using CTA versus functional testing for CAD diagnosis in symptomatic patients.   Clinical outcomes of CAD also depend on the effectiveness of treatment, not just on diagnosis.  Thus, there are confounding variables affecting the results of the study.  Moreover, the study cannot extend its results to everyone as it only includes men over 45 years old or women over 50 years old in the trial.

References:

  1. Lloyd-jones D, Adams R, Carnethon M, et al. Heart disease and stroke statistics–2009 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation. 2009;119(3):e21-181.
  2. Cassar A, Holmes DR, Rihal CS, Gersh BJ. Chronic coronary artery disease: diagnosis and management. Mayo Clin Proc. 2009;84(12):1130-46.
  3. Douglas PS, Hoffmann U, Patel MR, et al. Outcomes of anatomical versus functional testing for coronary artery disease. N Engl J Med. 2015;372(14):1291-300.
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