Diagnostic and prognostic significance of ischemic electrocardiographic changes with regadenoson-stress myocardial perfusion imaging

BACKGROUND

The diagnostic and prognostic value of regadenoson-induced ST-segment depression (ST↓) is not defined. Due to the low incidence of ST↓ ≥1.0 mm with vasodilator stress, a lower threshold to define ischemic ECG response may provide improved clinical utility.

METHODS

We conducted a retrospective cohort study of patients who underwent regadenoson-stress SPECT myocardial perfusion imaging (MPI) followed by coronary angiography within 6 months. Ischemic ST↓ was defined as ≥0.5 mm. The prevalence of angiographically severe coronary artery disease (CAD) and the rates of major adverse cardiac events (MACE) including cardiac death, myocardial infarction, and coronary revascularization were determined.

RESULTS

In a diagnostic cohort of 629 subjects, 117 (18.6%) had ST↓ ≥0.5 mm. Severe CAD was more prevalent in the ST↓ ≥0.5 vs ST <0.5 group (13.7% vs 5.3%, P = .001). Among patients with normal MPI (n = 229), the prevalence of severe CAD was higher in the ST↓ ≥0.5 group (8.2% vs 2.2%, P = .04). Adjusting for clinical and imaging covariates, ST↓ ≥0.5 mm was independently predictive of severe CAD [odds ratio = 3.37, 95% confidence interval (CI) = 1.67-6.83, P = .001], and provided incremental diagnostic value (Chi square increment = 10.3, P = .001). In an outcome cohort of 748 subjects, after adjusting for clinical and imaging covariates, ST↓ ≥0.5 mm was associated with increased MACE rate in the entire cohort [hazard ratio = 1.41, CI 1.01-1.96, P = .04] and in the subgroup of patients with normal MPI [hazard ratio = 2.2, CI 1.11-4.39, P = .02], and provided incremental prognostic value (Chi square increment = 3.9, P = .049). A diagnostic ST↓ threshold of 0.5 mm provided greater discriminatory capacity than a 1.0 mm cutoff (P = .03).

CONCLUSIONS

Among patients selected to undergo coronary angiography, regadenoson-induced ST↓ ≥0.5 mm was associated with higher rates of severe CAD and MACE, irrespective of MPI finding.

The prognostic value of transient ischemic dilatation with otherwise normal SPECT myocardial perfusion imaging: a cautionary note in patients with diabetes and coronary artery disease

BACKGROUND

The prognostic implications of transient ischemic dilatation (TID) of the left ventricle with otherwise normal single-photon emission computed tomography myocardial perfusion imaging (MPI) remain controversial. Whether this finding may have prognostic implications only in high-risk populations, such as patients with diabetes or manifest coronary artery disease (CAD), is uncertain.

METHODS

We conducted a prospective cohort study of 1,236 consecutive patients with normal (99m)Tc-sestamibi MPI, defined as normal perfusion (summed stress score = 0) and normal left ventricle volume and function. TID was defined as >2 standard deviations above the mean of patients with low likelihood of CAD.

RESULTS

The study subjects were followed for 27 ± 9 months. The 76 (6%) patients with TID had a greater rate of cardiac death or myocardial infarction (MI) [4 (5.3%) vs 11 (0.6%), P = .003] independent of covariates [hazard ratio = 6.4, P = .004]. This finding was entirely derived from the subgroup of 294 patients with diabetes or CAD [4 (13.3%) with TID vs 1 (0.4%) without TID, P = .001] independent of covariates. However, TID was not predictive of cardiac death or MI among the 941 patients without diabetes or CAD. Furthermore, TID was not predictive of coronary revascularization.

CONCLUSIONS

This study confirms a benign prognosis of TID with otherwise normal MPI in patients without diabetes or CAD, but cautions against extending this conclusion to high-risk individuals, particularly those with diabetes or CAD.