Approximately 13 percent of patients referred for primary PCI may have normal or near-normal coronary arteries on angiography, according to a study in the May issue of the American Journal of Cardiology.

Sandhir B. Prasad, MBBS, and colleagues from the Westmead Hospital in Westmead, Australia, sought to determine the prevalence, as well as clinical and electrocardiographic correlates, of patients referred for primary PCI, who had angiographically normal coronary arteries.

The researchers reviewed data for 690 consecutive patients with STEMI referred for primary PCI within a metropolitan-area, tertiary-care provider.

Overall, the investigators found that 594 patients had an identifiable culprit lesion, while 87 (13 percent) had either normal coronary arteries or minor disease only and were identified as a normal coronary artery group. They excluded nine patients with significant coronary artery disease, but no identifiable culprit lesions.

The authors observed that the patients in the normal coronaries group were younger and had fewer risk factors.

On review of the ECGs, the researchers found that 55 percent of patients in the normal coronaries group had ST-elevation criteria for STEMI (vs. 93 percent in the control group), but the ECG was considered consistent with a diagnosis of STEMI by both observers in only 33 percent (vs. 92 percent in the control group).

The left branch bundle block independently correlated with normal coronary arteries on multivariate analysis at an odds ratio of 0.016, the authors wrote. The discharge diagnosis in the normal coronaries group was predominantly pericarditis (72 patients; 83 percent).

In conclusion, Prasad and colleagues reported that the prevalence of angiographically normal coronary arteries in patients referred for primary PCI was 13 percent.

Electrocardiographic correlation suggested that this can be reduced by adherence to conventional electrocardiographic criteria for STEMI diagnosis and review of ECGs by experienced clinicians, the researchers said.

“The central role of detailed ECG analysis in avoiding misdiagnosis and false referral is a key finding of this study,” Prasad and colleagues concluded. “Diligent adherence to electrocardiographic criteria for STEMI diagnosis could have excluded 45 percent of patients in the normal coronaries group.”