Enhanced prognostic stratification of cad patients with dilated left ventricle by stress and rest functional parameters and 99mTc-tetrofosmin Gated-SPECT.

Purpose: To evaluate whether the post-stress and rest functional parameters, measured by Gated-SPECT, have incremental prognostic value compared with perfusion parameters in predicting cardiac events (CE), in a population of CAD patients with dilated LV.

Materials And Methods: A total of 670 consecutive patients (mean age: 62; range 29-86 yrs.) underwent conventional diagnostic 2-day gated-SPECT with 99mTc-tetrofosmin (55% exercise stress test, 45% dip stress): 605 patients (mean age: 62 yrs., range: 34-86 yrs.) had known or suspected CAD, whereas 65 (mean age: 60 yrs, range: 29-80 yrs) had low pre-test likelihood of CAD (<10%), a normal post-stress perfusion scan and no hypertension. Fifty-three percent of CAD patients had a history of MI. Perfusion was analyzed on ungated images using 20 segments scored on a 5-point scale (0=normal, 4=no uptake), while wall thickening was assessed visually on stress/rest end-systolic images using a 4-point score (0=normal, 3=absence of WT). LVEF and volumes were calculated using an automatic algorithm. Post-stress and rest ratio were determined for both end-diastolic and end-systolic volume, while the post-stress LVEF change (d-LVEF) was calculated according to the following formula: (Stress LVEF-rest LVEF)/rest LVEF*100.

Results: By using a cutoff value of 126 ml for rest-EDV, and of 68 ml for rest-ESV we found a LV dilation in 129/605 patients (21%). These thresholds were the mean values plus two standard deviations obtained in the control group. 111/129 (86%) were followed up for a mean period of 147.0 months. 83 of 111 (75%) patients had a history of MI and forty three (39%) had undergone surgical revascularizations. During the follow-up, 21 events (5 cardiac deaths, 3 nonfatal MI, 13 late revascularizations) occurred. All post-stress perfusion and functional parameters were more compromised in patients with CE compared with patients without events, but only rest EDV, rest ESV, post-stress ESV and WT-SSS reached statistical significance (201 ml vs 176 ml; p=0.035; 137 ml vs 113 ml; p=0.047; 143 ml vs 117 ml; p=0.034, 19 vs 15; p=0.048, respectively). Multivariate Cox proportional analysis demonstrated that stress ESV added significantly prognostic information over WT-SSS in predicting CE (p=0.046).

Conclusions: Stress ESV has incremental prognostic value compared with wall thickening in predicting CE, in CAD patients with dilated cardiomyopathy. Perfusion parameters failed to show prognostic information in these patients.