Effects of Impella support level on coronary blood flow velocity measured by transthoracic Doppler echocardiography.

UNLABELLED: Previous invasive studies on the Impella device (Abiomed, Danvers, MA, USA) have reported that its effect increases coronary artery perfusion. However, non-invasive evaluation using transthoracic Doppler echocardiography (TTDE) remains limited. We assessed the effects of different Impella support levels on coronary blood flow velocity using TTDE in four patients: two with ST-elevation myocardial infarction (STEMI), one with acute myocarditis, and one with myocardial infarction with non-obstructive coronary arteries (MINOCA) due to coronary spasm. The peak diastolic flow velocity (DPV) at the distal left anterior descending artery was measured for a surrogate of coronary blood flow at various Impella flow settings. In STEMI patients, DPV decreased in parallel with stepwise reductions in Impella support levels. In contrast, patients with acute myocarditis and MINOCA exhibited no significant DPV changes despite adjustments in support levels. These findings suggest that the impact of Impella on coronary flow velocity varies according to underlying disease pathology. In STEMI patients post-percutaneous coronary intervention, Impella-induced left ventricular unloading appears to enhance coronary perfusion, while in cases of myocarditis and MINOCA, microvascular dysfunction and other pathophysiological factors may limit this effect. LEARNING OBJECTIVES: This non-invasive evaluation used transthoracic Doppler echocardiography to assess the effect of Impella on coronary flow, revealing disease-specific differences. Patients with extensive anterior ST-elevation myocardial infarction showed a support-level-dependent increase in left anterior descending artery flow velocity. In contrast, those with acute myocarditis and myocardial infarction with non-obstructive coronary arteries showed no consistent changes. This suggests the beneficial effect may be dependent on the underlying pathology.