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SPECT Summed Stress Score — EECC MCQ

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ModerateCardiac ImagingSPECT Summed Stress ScoreEECC

A 55-year-old man undergoes stress perfusion SPECT for suspected CAD. His stress images show a reversible perfusion defect in the inferolateral wall. Rest images are normal. The interpreting physician reports this as a 'summed stress score' (SSS) of 12. What does this score indicate?

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Correct answer: B — SSS ≥8-13 indicates moderate ischaemic burden affecting 10-20% of the LV myocardium — this level of ischaemia supports consideration of coronary angiography and revascularisation based on the total ischaemic burden

SPECT perfusion scoring uses a 17-segment model with each segment scored 0-4 (0=normal, 1=mildly reduced, 2=moderately reduced, 3=severely reduced, 4=absent uptake). Summed scores: SSS (summed stress score): total perfusion abnormality at stress; SRS (summed rest score): total abnormality at rest (= scar); SDS (summed difference score) = SSS - SRS = ischaemia. Interpretation: SSS <4 = normal; 4-7 = mildly abnormal (~5-10% LV ischaemia); 8-13 = moderately abnormal (~10-20%); >13 = severely abnormal (>20%). Prognostic significance: ischaemic burden >10% of LV myocardium is associated with higher event rates and potential benefit from revascularisation. This patient's SSS 12 with normal rest = moderate ischaemia (~15% LV), supporting coronary angiography. The 2024 ESC CCS Guidelines integrate ischaemic burden from functional imaging into revascularisation decision-making.

Reference: ESC (2024): CCS; ASNC Guidelines