Stress-Scintigraphy versus contrast stress-echocardiography for prediction of hard cardiac events

Objectives: We compared the long-term prognosis of subjects without prior cardiac disease who underwent either vasodilator single-photon emission computed tomography (SPECT) or contrast stress-echocardiography (cSE) for suspected coronary artery disease (CAD). Background: The routine use of ultrasound contrast media during cSE improves wall motion assessment and test feasibility, but the prognostic value of cSE in comparison with SPECT is not known. Methods: Subjects who underwent vasodilator SPECT or cSE between 2008 and 2012 for suspected CAD but no history of cardiac disease were included. We compared the prognostic value of each method for combined all-cause death and non-fatal myocardial infarction, and their positive predictive value for angiographically obstructive CAD. Results: 1387 subjects were selected, 497 who underwent SPECT and 890 cSE. During 4 years of mean follow-up there were 78 hard events in the cSE group and 51 in the SPECT group. Event-free survival in subjects testing positive for ischemia, either with SPECT or cSE, was significantly worse both in the overall population and after propensity-matching patients 1:1 for baseline characteristics (p=0.032 for SPECT and p<0.001 for cSE). In multivariable analyses (entire group or splitted SPECT or cSE subgroups) SPECT or cSE demonstrated significant stratification capability, an ischemic test doubling (SPECT) or more than doubling (cSE) the risk of future hard events independently from other variables. Positive predictive value of SPECT for the diagnosis of obstructive CAD was inferior to cSE, (PPV=63% vs 89% respectively, p<0.001). Conclusion: Our study suggests that SPECT and cSE have comparable significant prognostic capability, with cSE demonstrating better diagnostic positive predictive value for CAD. The absence of ionizing radiation and anticipated lower direct and also indirect costs from higher positive predictive value, suggest that cSE may be preferable to SPECT as a gatekeeper in subjects without a prior history of CAD.