Adenosine Tc-99m Tetrofosmin SPECT in Differentiation of Ischemic From Nonischemic Cardiomyopathy in Patients With LV Systolic Dysfunction

Prognostic Value of Stress CMR Perfusion Imaging in Patients With Reduced Left Ventricular Function

OBJECTIVES

The aim of this study was to investigate the prognostic value of stress cardiac magnetic resonance imaging (CMR) in patients with reduced left ventricular (LV) systolic function.

BACKGROUND

Patients with ischemic cardiomyopathy are at risk from both myocardial ischemia and heart failure. Invasive testing is often used as the first-line investigation, and there is limited evidence as to whether stress testing can effectively provide risk stratification.

METHODS

In this substudy of a multicenter registry from 13 U.S. centers, patients with reduced LV ejection fraction (<50%), referred for stress CMR for suspected myocardial ischemia, were included. The primary outcome was cardiovascular death or nonfatal myocardial infarction. The secondary outcome was a composite of cardiovascular death, nonfatal myocardial infarction, hospitalization for unstable angina or congestive heart failure, and unplanned late coronary artery bypass graft surgery.

RESULTS

Among 582 patients (mean age 62 ± 12 years, 34% women), 40% had a history of congestive heart failure, and the median LV ejection fraction was 39% (interquartile range: 28% to 45%). At median follow-up of 5.0 years, 97 patients had experienced the primary outcome, and 182 patients had experienced the secondary outcome. Patients with no CMR evidence of ischemia or late gadolinium enhancement (LGE) experienced an annual primary outcome event rate of 1.1%. The presence of ischemia, LGE, or both was associated with higher event rates. In a multivariate model adjusted for clinical covariates, ischemia and LGE were independent predictors of the primary (hazard ratio [HR]: 2.63; 95% confidence interval [CI]: 1.68 to 4.14; p < 0.001; and HR: 1.86; 95% CI: 1.05 to 3.29; p = 0.03) and secondary (HR: 2.14; 95% CI: 1.55 to 2.95; p < 0.001; and HR 1.70; 95% CI: 1.16 to 2.49; p = 0.007) outcomes. The addition of ischemia and LGE led to improved model discrimination for the primary outcome (change in C statistic from 0.715 to 0.765; p = 0.02). The presence and extent of ischemia were associated with higher rates of use of downstream coronary angiography, revascularization, and cost of care spent on ischemia testing.

CONCLUSIONS

Stress CMR was effective in risk-stratifying patients with reduced LV ejection fractions. (Stress CMR Perfusion Imaging in the United States [SPINS] Study; NCT03192891).

Dyssynchrony contributes to false-positive myocardial perfusion SPECT results in patients with stable angina

AIM

We designed this study to evaluate the possibility that dyssynchrony might lead to false-positive myocardial perfusion single photon emission computed tomography myocardial perfusion image (MPS) results in stable angina patients.

METHODS AND RESULTS

This study included 61 patients with both clinically diagnosed stable angina and quantitative MPS results who underwent coronary angiography. The patients were divided into two groups: those who had positive MPS results and normal coronary angiography (Group I, n = 28, 64.05 ± 10.14 years, 11 males and 17 females) and those who had positive MPS results and significant coronary lesions as determined by coronary angiography (Group II, n = 33, 69.2 ± 10.4 years, 14 males and 19 females). The maximal difference in time-to-peak myocardial sustained systolic velocity among all 12 left ventricular (LV) segments (maximal difference in TS) was significantly delayed in Group I as compared with Group II (125.00 ± 46.10 vs. 87.33 ± 40.53 ms, P=0.001). The standard deviation of the time-to-peak myocardial sustained systolic velocity of all 12 LV segments (TS-SD) was also significantly different in the two groups (45.12 ± 19.25 vs. 30.10 ± 15.80 , P=0.002).

CONCLUSION

Dyssynchrony may be a cause of false-positive quantitative MPS results, even if patients have narrow QRS complexes on ECG. Dyssynchrony index can increase the specificity of quantitative MPS in stable angina patients.

Ischemic cardiomyopathy: a clinical nuclear cardiology perspective

Ischemic cardiomyopathy results from severe extensive coronary artery disease, which is associated with left ventricular dysfunction and also, in many cases, with significant left ventricular dilatation. Mortality is high, especially in patients who satisfy myocardial viability criteria but who have not undergone revascularization. Although age, exercise capacity and comorbidity influence survival, the most important prognostic factors are the extent of the ischemia, myocardial viability and left ventricular remodeling, all of which can be successfully evaluated by gated myocardial perfusion single-photon emission computed tomography (SPECT).