Acute alterations in blood lactate in the setting of transient stress induced myocardial ischaemia

<p dir="ltr">An elevation in resting venous blood lactate ([La−]b) levels in conditions of myocardial hypoperfusion is associated with adverse prognosis and survival. This investigation aimed to assess changes in venous [La−]b levels induced by dobutamine stress in the presence and absence of myocardial ischaemia and adverse outcomes at 1 year. Four hundred and four consecutive patients (mean age 70 ± 10 years, 243 male) reporting chest pain underwent dobutamine stress echocardiography (DSE) and were categorised as ischaemic (IS) or non‐ischaemic (NI) responders. Conventional and global longitudinal strain (GLS) echocardiographic measures were recorded at rest. Venous [La−]b samples were acquired at rest, peak stress and 1, 3, 5 and 10 min into recovery using a commercially available Lactate Pro 2 device. There were no significant differences in [La−]b concentrations between IS (1.75 ± 0.76 mmol L−1) and NI (1.73 ± 0.60 mmol L−1) responders at baseline (P = 0.592). However, [La−]b concentrations were significantly greater at peak stress (1.83 ± 0.57 vs. 1.68 ± 0.60 mmol L−1), 1 (1.90 ± 0.56 vs. 1.73 ± 0.71 mmol L−1), 3 (1.97 ± 0.56 vs. 1.73 ± 0.71 mmol L−1), 5 (1.98 ± 0.60 vs. 1.74 ± 0.70 mmol L−1) and 10 min (2.01 ± 0.63 vs. 1.76 ± 0.71 mmol L−1) into recovery between IS and NI responders (all P < 0.001). GLS was significantly lower in IS compared to NI (−15.5 ± 2.9 vs. −16.2% ± 2.7%, P = 0.02) responders at baseline. In patients who experienced an adverse cardiac event during 1 year of follow‐up, GLS (−14.4 ± 2.7 vs. −16.1% ± 2.8%, P < 0.001) and [La−]b concentrations were significantly lower at baseline (1.54 ± 0.55 vs. 1.78 ± 0.70 mmol L−1, P = 0.02), as were [La−]b concentrations at 5 (1.68 ± 0.55 vs. 1.88 ± 0.68 mmol L−1, P = 0.04) and 10 min (1.70 ± 0.56 vs. 1.93 ± 0.71 mmol L−1, P = 0.02) into recovery compared to patients who did not experience an adverse event. GLS (hazard ration (HR) 1.21; 95% CI: 1.11–1.33, P < 0.001) and [La−]b concentrations at 10 min into recovery (HR 0.54; 95% CI: 0.33–0.85, P = 0.01) were significant independent predictors of an adverse event. Transient myocardial ischaemia is associated with a significant elevation in [La−]b concentrations, which extends into the recovery period, compared to NI responders. A blunted metabolic response to dobutamine stress and attenuated longitudinal myocardial mechanics are independently associated with short‐term adverse events.</p>