Non-invasive myocardial work index identifies acute coronary occlusion in patients with non-ST-segment elevation-acute coronary syndrome

Abstract

Aims: Acute coronary artery occlusion (ACO) occurs in ∼30% of patients with non-ST-segment elevation-acute coronary syndrome (NSTE-ACS). We investigated the ability of a regional non-invasive myocardial work index (MWI) to identify ACO.

Methods and results: Segmental strain analysis was performed before coronary angiography in 126 patients with NSTE-ACS. Left ventricular (LV) pressure was estimated non-invasively using a standard waveform fitted to valvular events and scaled to systolic blood pressure. MWI was calculated as the area of the LV pressure-strain loop. Empirical cut-off values were set to identify segmental systolic dysfunction for MWI (<1700 mmHg %) and strain (more than -14%). The number of dysfunctional segments was used in ROC analysis to identify ACO. The presence of ≥4 adjacent dysfunctional segments assessed by MWI was significantly better than both global strain and ejection fraction at detecting the occurrence of ACO (P < 0.05). Regional MWI had a higher sensitivity (81 vs. 78%) and especially specificity (82 vs. 65%) compared with regional strain. Logistic regression demonstrated that elevated systolic blood pressure significantly decreased the probability of actual ACO in a patient with an area of impaired regional strain.

Conclusion: The presence of a region of reduced MWI in patients with NSTE-ACS identified patients with ACO and was superior to all other parameters. The regional MWI was able to account for the influence of systolic blood pressure on regional contraction. We therefore propose that MWI may serve as an important clinical tool for selecting patients in need of prompt invasive treatment.

Keywords: acute coronary syndrome; echocardiography; haemodynamics; hypertension; myocardial contraction.