The clinical importance of electrocardiographic changes during pharmacologic stress testing with radionuclide myocardial perfusion imaging

Diagnostic safety of a machine learning-based automatic patient selection algorithm for stress-only myocardial perfusion SPECT

BACKGROUND

Stress-only myocardial perfusion imaging (MPI) markedly reduces radiation dose, scanning time, and cost. We developed an automated clinical algorithm to safely cancel unnecessary rest imaging with high sensitivity for obstructive coronary artery disease (CAD).

METHODS AND RESULTS

Patients without known CAD undergoing both MPI and invasive coronary angiography from REFINE SPECT were studied. A machine learning score (MLS) for prediction of obstructive CAD was generated using stress-only MPI and pre-test clinical variables. An MLS threshold with a pre-defined sensitivity of 95% was applied to the automated patient selection algorithm. Obstructive CAD was present in 1309/2079 (63%) patients. MLS had higher area under the receiver operator characteristic curve (AUC) for prediction of CAD than reader diagnosis and TPD (0.84 vs 0.70 vs 0.78, P < .01). An MLS threshold of 0.29 had superior sensitivity than reader diagnosis and TPD for obstructive CAD (95% vs 87% vs 87%, P < .01) and high-risk CAD, defined as stenosis of the left main, proximal left anterior descending, or triple-vessel CAD (sensitivity 96% vs 89% vs 90%, P < .01).

CONCLUSIONS

The MLS is highly sensitive for prediction of both obstructive and high-risk CAD from stress-only MPI and can be applied to a stress-first protocol for automatic cancellation of unnecessary rest imaging.

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

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.

Positive vasodilator stress ECG with normal myocardial perfusion imaging and its correlation with coronary angiographic findings in African Americans and Hispanics

BACKGROUND

Ischemic electrocardiographic (ECG) changes during vasodilator stress testing (VST) in the presence of abnormal myocardial perfusion imaging (MPI) are uncommon and are associated with presence of multivessel coronary artery disease (CAD). However, there is a paucity of data regarding the significance of ischemic ECG changes during VST with normal MPI in general, and especially among African Americans and Hispanics.

HYPOTHESIS

Ischemic changes during VST with normal MPI are associated with significant CAD.

METHODS

A retrospective review was done of 2945 patients undergoing VST.

RESULTS

Only 20 patients (0.7%) had positive ECG changes with normal MPI. Their demographics were: 60% Hispanic, 40% African American; 85% female; mean age 63 ± 11 years; history of hypertension 80%, diabetes 50%, and dyslipidemia 75%; smokers 30%; atypical chest pain 60%, and typical chest pain 40%. Of these 20 patients, 12 patients underwent coronary angiography. All 12 had significant CAD; nine (75%) had multivessel disease and 3 (25%) had single-vessel disease. Prevalence of clinical variables and risk factors for CAD were similar among both the groups who did and did not undergo coronary angiography.

CONCLUSIONS

Among African Americans and Hispanics, ischemic ECG changes during VST with normal MPI are likely to be associated with significant CAD and may warrant coronary angiography to assess presence and extent of CAD.

Patients with adenosine-induced ST-segment depressions and normal myocardial perfusion imaging: cardiac outcomes at 24 months

BACKGROUND

The significance of ischemic ECG changes during adenosine infusion in patients with normal myocardial perfusion imaging (MPI) is controversial. We evaluated the prevalence of, and defined the predictors for, severe coronary artery disease (CAD) in patients with such discordant findings.

METHODS

The findings of 3700 adenosine MPI studies performed at our institution between June 2005 and March 2009 were reviewed.

RESULTS

Data for 76 patients who had not previously undergone coronary revascularization and who had sufficient follow-up were analyzed; 22 (29%) were referred for coronary angiography and 10 (13%) underwent revascularization. None had left main disease and only three (14%) had multivessel disease. Diabetes mellitus was more prevalent (70% vs. 23%; P = .010) and ischemic ST-segment depressions more often lasted >5 minutes (50% vs. 15%; P = 0.021) in patients undergoing revascularization. During a 24 ± 13 month follow-up period, there were no deaths or myocardial infarctions, while an eleventh patient underwent revascularization 19 months after MPI.

CONCLUSIONS

In the presence of normal MPI, the specificity of ischemic ECG changes during adenosine infusion for the detection of severe obstructive CAD is poor, although patients with multiple coronary risk factors, particularly diabetes mellitus, should undergo further investigation.

Stress-induced abnormalities in myocardial perfusion imaging that are not related to perfusion but are of diagnostic and prognostic importance

INTRODUCTION

Certain stress-induced ancillary findings on myocardial perfusion scintigraphy increase the likelihood that the patient has coronary artery disease (CAD); furthermore, among CAD patients, they indicate more severe and extensive disease, placing these patients at higher risk for future cardiac events. Indeed, in studies with no obvious perfusion defect yet with serious CAD--for example, balanced ischemia--it can be these high-risk findings that necessitate invasive intervention.

DISCUSSION

Besides reversible perfusion defects, such findings include increased pulmonary radiotracer uptake, transient cavity dilatation, increased end-diastolic or end-systolic volume, decreased post-stress ejection fraction, and increased right ventricular tracer uptake on stress images. The pathophysiology underlying these findings is clearly different as they do not always occur together, and each independently predicts more severe and extensive CAD. In the current review, these findings are defined and their significance in diagnosing patients with suspected or known CAD is discussed.