Exercise intolerance in a man with ischaemic cardiomyopathy and biventricular pacing

Clinical introduction A patient in his 60s with a history of ischaemic cardiomyopathy and severely reduced left ventricular ejection fraction of 20% presents with worsening dyspnoea on exertion. He is tolerating therapeutic doses of guideline-directed medical therapy including sacubitril-valsartan, carvedilol, spironolactone and empagliflozin, and has a biventricular implantable cardiac defibrillator. He undergoes cardiopulmonary exercise testing (CPET) using the treadmill-modified Bruce protocol and is found to have a severely reduced peak oxygen consumption (VO2) (14.9 mL/kg/min) despite maximal effort. The test was stopped due to shortness of breath. Plots 1 and 2 from the CPET are shown in figure 1A and B. Figure 1(A) Oxygen consumption (VO2) (empty red squares) and carbon dioxide production (VCO2, blue dots). (B) Heart rate (HR) (beats per minute, brown dots) and oxygen pulse (VO2/HR, empty red squares). Question What is the most likely...
Source: Heart - Category: Cardiology Authors: Tags: Arrhythmias and sudden death Source Type: research