A study found that obstructive coronary artery disease (CAD) patients undergoing invasive coronary angiography (ICA) evaluation for ischemic heart disease have significantly more cardiac events than patients with normal or near normal coronary arteries (NNCA). The results appeared in Clinical Cardiology.
In this study, researchers assessed 925 patients who underwent an initial ICA at the University of Virginia for suspected CAD between January 2012 and December 2013. Exclusion criteria consisted of patients with known CAD, history of myocardial infarction (MI), emergent indications for ICA (such as ST-elevation MI, cardiogenic shock, or post-cardiac arrest), ICAs performed for preoperative evaluation for transplant or cardiothoracic surgery or evaluation of non-ischemic cardiomyopathy or congenital heart disease.
Findings and Limitations
Subsequent to an average follow-up of six years, the results showed a significant decrease in survival free from cardiac death (CD)/nonfatal myocardial infarction (NFMI), and total cardiac events in patients with obstructive CAD compared to patients with NNCAs or nonobstructive CAD. Surprisingly, the investigators observed, there was still no difference in annual rates of CD/NFMI (1.6% vs. 1.9% per year, p = .44), or total cardiac events (1.7% vs. 2.2% per year, p = .61) observed between patients with NNCAs and nonobstructive CAD.
In terms of limitations, there were several. First, this was a single-center study comprised of a limited number of patients in the nonobstructive CAD group, which may limit the ability to detect small statistical differences with low-event rates. Also, because the was retrospective in design, FFR was not performed routinely in the entire patient population.
Interpreting the Findings
“A major finding of the current study is that patients who were found to have nonobstructive CAD, defined as 21%–49% stenosis, had similar low-event rates to patients found to have normal or NNCA at angiography at a median of 6 years of follow-up. Patients with NSTEMI and either normal or NNCA or nonobstructive CAD had a prognosis similar to patients referred for coronary angiography for chest pain or following an abnormal stress test. No gender differences were observed in outcomes regardless of angiographic classification,” the researchers concluded.
“We speculate that these low-event rates may be secondary to enhanced medical therapy after the detection of coronary plaque at angiography, albeit nonobstructive. This is consistent with what has been observed for patients with nonobstructive CAD in studies using CCTA.”