The prognostic value of non-perfusion variables obtained during vasodilator stress myocardial perfusion imaging

Abstract

Myocardial perfusion imaging (MPI) is an established diagnostic test that provides useful prognostic data in patients with known or suspected coronary artery disease. In more than half of the patients referred for stress testing, vasodilator stress is used in lieu of exercise. Unlike exercise, vasodilator stress does not provide information on exercise and functional capacity, heart rate recovery, and chronotropy, and ECG changes are less frequent. These non-perfusion data provide important prognostic and patient management information. Further, event rates in patients undergoing vasodilator MPI are higher than in those undergoing exercise MPI and even in those with normal images probably due to higher pretest risk. However, there are a number of non-perfusion variables that are obtained during vasodilator stress testing, which have prognostic relevance but their use has not been well emphasized. The purpose of this review is to summarize the prognostic values of these non-perfusion data obtained during vasodilator MPI.

The blood pressure response to vasodilator stress does not provide independent prognostic information

“…5 This prognostic data are important for risk stratification and can help guide clinical management of patients. The use of nonperfusion variables to augment the prognostic data provided by MPI is especially important when vasodilator stress is used in lieu of exercise, since patients referred for vasodilator MPI are at higher risk than those referred for exercise MPI, irrespective of the perfusion pattern, 6 and since functional capacity, a very strong prognostic index, 7 cannot be assessed when using vasodilators.…”

Myocardial stunning by gated SPECT: An old tool reinvented in a stunning turn

“…Lastly, we need to explore whether WT-SDS adds incremental information to other non-perfusion variables such as transient ischemic dilation, 24,25 STsegment shift, 26,27 heart rate response, [28][29][30] myocardial blood flow reserve, [31][32][33] LV dyssynchrony, 14,34,35 and other non-perfusion variables. 23 In conclusion, the study by Bestetti et al 22 reintroduced a long forgotten parameter, WT-SDS, and demonstrated that it correlates better with ischemic burden than LVEF reserve and therefore may improve the detection of myocardial stunning. Larger studies are needed to validate this score, measure its interobserver and intraobserver variability, assess whether regional WT-SDS is better than global score, apply it in cohorts with normal and abnormal myocardial perfusion, and evaluate whether it adds diagnostic and prognostic value beyond LVEF, mechanical dyssynchrony, TID, and other non-perfusion variables.…”

“…Also, the incremental information provided by some non-perfusion variables may be dependent on the myocardial perfusion pattern, as recently reviewed. 23 It is of great interest to examine whether WT-SDS or other indicators of myocardial stunning may provide useful information in patients with normal perfusion pattern, but these patients were excluded from this study by design. Lastly, we need to explore whether WT-SDS adds incremental information to other non-perfusion variables such as transient ischemic dilation, 24,25 STsegment shift, 26,27 heart rate response, [28][29][30] myocardial blood flow reserve, [31][32][33] LV dyssynchrony, 14,34,35 and other non-perfusion variables.…”

Risk stratification for renal transplantation: A role for heart rate response?

“…8,9 More recently, several non-perfusion variables measured during stress MPI have been identified in the search for added prognostic information, and heart rate response (HRR) to vasodilator stress has appeared promising. 10 Large retrospective cohorts have shown that blunted HRR is not only an independent predictor of cardiovascular events and all-cause mortality, but may also reclassify up to 20% of individuals when added to traditional risk factors and MPI results. 11,12 The added prognostic impact of HRR has been reproduced in patients with ESRD, 9 but studies examining the role of HRR in predicting perioperative or long-term events in renal transplant patients are lacking.…”