Abstract 9711: Unexplained Dyspnea on Exertion: The Difference the Right Test Can Make

Abstract

A 66-year-old male with past history of coronary atherosclerosis by angiography was referred for chronic dyspnea. He is a pastor and had noted dyspnea with prolonged standing or walking that resolved with sitting. Serial orthostatic vitals and natriuretic peptides were normal. Subsequent diagnostics included normal pulmonary function and ventilation-perfusion tests, and echocardiography with normal biventricular function, sizes, and estimated pressures. Given ongoing dyspnea, he underwent supine invasive cardiopulmonary exercise testing (iCPET). Resting invasive pressures and cardiac output were normal. At peak exercise, exertional dyspnea was absent but pressures increased to mean PAP 40 and PCWP 28 with preserved cardiac output and 77% predicted maximal aerobic capacity (pVO2). He was diagnosed with exercise induced heart failure with preserved ejection fraction and started on furosemide and spironolactone. On follow-up, he reported worsened dyspnea on therapy, most notably when upright. Stress cardiac MRI showed no scar. Given the positional nature of his symptoms, an iCPET was repeated in the upright position. His diuretics were stopped. Resting supine measurements were similar to the prior iCPET. Upright resting to peak exercise pressures changed minimally ( Figure ). His profound dyspnea recurred at peak exertion as MAP dropped unexpectedly with paradoxical bradycardia (Bezold-Jarisch reflex) and 62% pVO2. His diagnosis was reclassified as cardiac preload failure. He was advised to increase fluid and salt intake alongside use of leg stockings which remarkably improved his upright and exercise dyspnea symptoms at follow-up. This case highlights an advantage of upright iCPET over supine diagnostics in the comprehensive evaluation of unexplained dyspnea. Cardiac preload failure is the failure to augment preload with exercise and is a common but under-recognized cause of dyspnea often undiagnosed during supine resting and exercise testing.