Anatomy vs physiology: Is that the question?

Excerpt

There is a general tenet in nuclear cardiology that the greater the underlying coronary stenosis, the higher the likelihood of functionally significant myocardial ischemia. This correlation is even stronger in the setting of a significant left main coronary stenosis or triple-vessel coronary artery disease (CAD) where the severity of ischemic defects is frequently profound and encumbering a large proportion of the myocardium. It is reported that nearly 95 % of patients with severe left main or 3-vessel CAD will have an abnormal stress myocardial perfusion SPECT.1,2 The remainder, with normal stress findings, are the focus of research examining the concept of balanced reduction in myocardial perfusion due to high risk CAD.3,4 In the current issue of the journal, Yokota et al5 examines the prevalence of severe left main or its equivalent triple-vessel CAD in the setting of normal stress myocardial perfusion findings. Of 256 symptomatic patients undergoing prompt coronary angiography following a normal stress myocardial perfusion scan, 7 % had left main and 10 % had 3-vessel CAD. These findings are consistent with prior research3 and suggest that the false negative rate for a normal stress myocardial perfusion SPECT, albeit a safety concern for most clinicians, is relatively modest. This report also includes prognostic findings in the setting of a normal stress SPECT and report an annual death rate of ~1.7 % in the 93 patients with significant CAD; a rate similar to the remaining 163 patients with nonobstructive CAD. This death rate is consistent with the hundreds of registry series reporting an annual death rate that is equated to low risk status in those with a normal stress myocardial perfusion SPECT scan.6 These low risk prognostic findings suggest that patients with a normal stress myocardial perfusion SPECT scan have few events and, even in the presence of underlying severe CAD, anatomic adaptations, such as collateralization, may be poorly documented but result in normalization of flow and improvement of clinical outcomes for these CAD patients. …