Cardiovascular disease (CVD) in respiratory impaired patients is a likely co-morbidity since key risk factors (e.g. tobacco use, age) are shared. As symptoms of dyspnea and chest tightness are non-specific, underlying CVD may too long remain undiagnosed; to the patient’s detriment. To determine the diagnostic value of CPET alone and as an addition to conventional cardiac exercise testing in detecting CVD in RI pts, we performed the following experiment.
92 subjects, (50M, 42F) were evaluated for persistent dyspnea by CPET utilizing a stationary bicycle and watt-ramp protocol. Each had a known respiratory disorder (COPD, asthma, sarcoid, RADS) under treatment. 68 of these were also cardiac stress tested over the same interval; with 56 patients considered “low-risk for ischemia”. CPET analysis was performed without knowledge of cardiac test results.
81 subjects exhibited a reduced work capacity (<85% of the VO2max pred.) with 65 (80%) exhibiting a pattern of respiratory limitation (Breathing reserve <15%; O2sat <89%; FEV1 >15% decline) at peak exercise. 16 (20%) manifest a CV limitation (VO2 AT <40% of VO2max; reduced O2/pulse). Of the latter CV-limited group, 10 (63%) tested “low-risk for ischemia”. All 16 patients underwent re-evaluation including medication changes and/or catheterization.
Respiratory impaired patients appear to be at risk for undetected concurrent cardiovascular disease. Even when utilized, conventional cardiac testing (combining exercise with ultrasound or scintiographic imaging) may overlook non-ischemic CVD. CPET, a metabolically based assessment of global cardiovascular function/oxygen delivery, is sensitive to non-ischemic cardiac dysfunction that may evade conventional cardiac stress testing.
Respiratory impaired patients pose particular challenges to clinical suspicion and diagnosis of concurrent cardiovascular disease by conventional cardiac testing modalities. CVD due to hypertension, valvular dysfunction, and primary myocardial disorders may evade cardiac stress testing that principally targets ischemia. A high index of suspicion for concurrent CVD coupled with selective use of CPET may help detect significant cardiovascular impairment and may lead to improved treatment.
Bohdan Pichurko, FCCP, None.