Predictive Value of Positive Exercise Testing only during Recovery Phase: Comparison with ECG-Gated SPECT

Purpose: The ST segment depression occurring only in the recovery phase of an exercise testing (ET) (↓STr) is relatively rare (2.3-15%). This study aimed to investigate possible associations between ↓STr and ECG-gated SPECT imaging alterations.

Methods: Observational study (April 2010–December 2012), including 92 consecutive patients with known or suspected CAD with ↓ST anytime (≥1 mm) during recovery on ET, and who underwent ECG-gated SPECT. Mean age was 60±9.9 years, 74 (80.4%) male. A 5-point score (0-normal; 4-no uptake) and a 6-point score (0-normal; 5-diskinesia) assessed perfusion and wall motion; LVEF assessed after ET. From ET data, ↓STr, blood pressure (BP), heart rate (HR), time of tolerance to exercise, functional capacity (MET), time to onset of ↓STr, and presence of arrhythmias were evaluated.

Results: Abnormal perfusion was found in 58 patients (63%), 60% had ischemia – either isolated or associated with fixed defect, 31 (33.7%) abnormal wall motion; LVEF mean 57.8±11.6%, ↓STr 184.9 ± 92.4 s, magnitude 1.2±0.3 mm, 10.4±2.7 MET; 16 pts (17.6%) had angina, 58 pts (63%) ventricular arrhythmias. There were significant differences between ↓STr on ET and perfusion regarding male gender (p<0.001, PPV=73%); early time of onset ↓STr [(< 3min) p=0.011, PPV=76.2%]; increased systolic BP ≤30mmHg during ET (p=0.002, PPV=91.3%); and typical angina (p=0.025, PPV=87.5%). Transient defect was associated with male gender (p=0.01), hypertension (p=0.04), and smoking (p=0.03). The PPV was 64% for ↓STr to the presence of perfusion or wall motion abnormalities, and LVEF decrease.

Conclusion: ↓STr on ET showed strong association with ECG-gated SPECT alterations.

Keywords: Exercise Stress Testing, Myocardial Perfusion Imaging, St Segment Depression, Recovery Phase.