Acute Changes in Myocardial Work during Isometric Exercise in Hypertensive Patients with Ischemic Heart Disease: A Case-Control Study

Background: The acute hemodynamic response to isometric exercise in hypertensive patients' ischemic heart disease (IHD) has been poorly investigated. The aim of this study was to assess acute changes in left ventricular myocardial work (MW) during isometric bilateral knee extension in patients with IHD. Methods: Twenty stable hypertensive patients with IHD and ten healthy, age-matched controls (HC) were enrolled. All subjects performed an isometric knee extension exercise at 30% of their maximal voluntary contraction. The effort was maintained for three minutes or until exhaustion. At baseline, at peak exercise, and after 10 min of recovery, echocardiography evaluation was performed and blood pressure (BP) and heart rate (HR) were measured. Results: The exercise was well tolerated by all subjects. At peak exercise, systolic BP in the IHD was significantly higher than HC (37.6 ± 7.2 vs. 8.4 ± 2.3 mmHg; p 0.002). The HC group had a greater increase in HR than IHD (19.7 ± 6.2 vs. 8.4 ± 2.2 bpm; p 0.009). The E/E' ratio increased in IHD and was unchanged in the control group. The global work index increased significantly in IHD compared to HC (+15% vs. +3%; p 0.026). Global constructive work increased significantly in IHD compared to HC (+29.8% vs. +7.4 respectively, p 0.031). Global wasted work increased by 92.3% in IHD and was unchanged in HC. The global work efficiency decreased in IHD (-18%), but was unchanged in HC (between-groups p 0.019). Stroke volume decreased in IHD and was unchanged in HC. Cardiac output was unchanged in IHD, while it increased in HC. Conclusion: In patients with hypertension and underlying IHD, an acute isometric load causes a great increase in systolic BP and LV filling pressure. It follows a mostly ineffective increase in MW that fails to maintain stroke volume.