Clinical research: cardiac imaging
Transient ischemic dilation ratio of the left ventricle is a significant predictor of future cardiac events in patients with otherwise normal myocardial perfusion SPECT

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Abstract

Objectives

This study evaluated the prognostic value of transient ischemic dilation (TID) of the left ventricle (LV) in patients with normal stress myocardial perfusion single photon emission computed tomography (MPS).

Background

The prognostic value of TID in patients with an otherwise normal MPS has not been defined.

Methods

We identified 1,560 patients who had normal stress MPS (436 vasodilator and 1,124 exercise stress), and no rest LV enlargement (Population 1) and followed up for 2.30 ± 0.67 years for hard events (HE) (cardiac death or myocardial infarction) and soft events (SE) (revascularization). Prediction of first HE or SE (total events [TE]) was evaluated by multivariable Cox analysis, which was also applied to a broader group of 2,037 patients (including patients with minimal defects (Population 2).

Results

In Population 1, there were 13 HE, 36 SE, and 42 TE. Patients in the highest TID quartile (TID ≥1.21) had a higher TE rate than others, regardless of stress type. By multivariable analysis, highest TID quartile was predictive of TE (p = 0.008). Other independent predictors of TE were age, typical angina, and diabetes. In Population 2, TID was also predictive of TE.

Conclusions

An entirely normal stress MPS study does not always imply an excellent prognosis. In patients with otherwise normal MPS, TID is an independent and incremental prognostic marker of TE even after significant clinical variables—age, typical angina, and diabetes—are accounted for. When TID is present, caution in making low-risk prognostic statements may be warranted, especially in patients with typical angina, the elderly, and diabetics. Our findings also appear to apply to the broader population of “normal” MPS, which included patients with minimal perfusion defects.

Abbreviations

CAD
coronary artery disease
CD
cardiac death
ECG
electrocardiogram
HE
hard cardiac events
LHR
lung-heart ratio
LV
left ventricle/ventricular
MI
myocardial infarction
MPS
myocardial perfusion single photon emission computed tomography
SE
soft cardiac events
SPECT
single photon emission computed tomography
SSS
summed stress scores
TE
total cardiac events
TID
transient ischemic dilation of the left ventricle
201Tl
thallium-201
99mTc
technetium-99m

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Supported, in part, by grants from Bristol-Myers Squibb Medical Imaging, Inc., Billerica, Massachusetts; and Fujisawa Healthcare, Inc., Deerfield, Illinois. Dr. Abidov is a Save A Heart Foundation/Max and Pauline Zimmer Family Foundation Research Fellow at Cedars-Sinai Medical Center, Los Angeles, California. Dr. James E. Udelson acted as Guest Editor for this manuscript.