Diastolic stress testing: similarities and differences between isometric handgrip and cycle echocardiography

Abstract

Cycle echocardiography (CE) is recommended for noninvasive diagnosis of diastolic dysfunction but can be limited by respiratory and movement artifact. Isometric handgrip echocardiography (IHE) is also a robust diastolic discriminator, while avoiding the limitations associated with dynamic exercise. This study sought to compare these two diastolic stress testing approaches. Twelve elderly individuals were recruited from the community (age 71 ± 6 yr). Heart rate, arterial blood pressure, and left ventricular (LV) diastolic function (via echocardiography) were assessed at rest and in response to 3 min of IHE at 40% of their maximal voluntary contraction, followed by 3 min of CE at 20 W. Both IHE and CE caused a significant increase in heart rate and blood pressure, leading to similar increases in myocardial oxygen demand. Both stressors also evoked a similar rise in the ratio between early LV mitral inflow velocity to early lateral annular velocity, a surrogate measure of LV filling pressure. The underlying mechanisms leading to these changes, however, were inherently different. IHE increased mean arterial pressure, and impaired myocardial relaxation, to a greater extent than CE. In contrast, CE augmented cardiac index, and increased early mitral filling velocity, to a great extent than IHE. In conclusion, for the first time, these data highlight several important similarities and differences between IHE and CE. That IHE avoids respiratory and movement artifact, while still serving as a robust diastolic discriminator, supports IHE as a strong alternative to CE for diastolic stress testing. NEW & NOTEWORTHY This is the first study to compare the diastolic stress response between isometric handgrip exercise and conventional cycle exercise. The data suggest that isometric handgrip echocardiography is comparable to conventional cycle echocardiography, both in terms of its hemodynamic challenge and global diastolic stress response. That isometric handgrip echocardiography eliminates both respiratory and movement artifact and is low cost and incredibly portable supports its integration into routine echocardiography exams.