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Biphasic Response Viability Assessment — EECC MCQ

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HardCardiac ImagingBiphasic Response Viability AssessmentEECC

A 65-year-old man undergoes dobutamine stress echocardiography for suspected CAD. At low-dose dobutamine (10 mcg/kg/min), an akinetic anterior wall segment becomes hypokinetic (improves). At peak dose (40 mcg/kg/min), the same segment becomes akinetic again (worsens). What does this biphasic response indicate?

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Correct answer: D — Myocardial viability with ischaemia — the biphasic response (improvement at low-dose, worsening at peak) indicates hibernating myocardium that is viable but ischaemic, and predicts functional recovery after revascularisation

The biphasic response on dobutamine stress echocardiography is the most specific predictor of myocardial viability and functional recovery after revascularisation. It indicates: (1) low-dose improvement: contractile reserve is present — viable myocytes respond to inotropic stimulation (hibernating myocardium); (2) peak-dose deterioration: the viable myocardium becomes ischaemic at higher heart rates due to flow-limiting coronary stenosis. Other viability patterns: sustained improvement (viable, less ischaemic); no change at any dose (likely scar). The 2024 ESC CCS Guidelines recommend viability assessment (dobutamine stress echo, CMR with LGE, or nuclear imaging) before revascularisation of chronically dysfunctional myocardium in ischaemic cardiomyopathy to identify patients most likely to benefit from revascularisation.

Reference: ESC (2024): CCS Guidelines; ASE/EACVI Stress Echo Guidelines