Systemic Sclerosis and Pulmonary Hypertension: The Great Masquerader.

Abstract

The cardiorespiratory involvement in systemic sclerosis quite invariably leads to shortness of breath,1 but the exact pathophysiology underlying this symptom might be difficult to decipher. A 72-year-old woman complained of dyspnea New York Heart Association III-IV after a diagnosis of systemic sclerosis. Echocardiography revealed a high probability of pulmonary hypertension; the left atrium was at the upper limit of normal (33 mL/m2) with reduced reservoir function, witnessed by a strain of 14% (Figure 1). At right heart catheterization, the patient showed a precapillary pulmonary hypertension with pulmonary vascular resistance of 6.8 WU. An invasive exercise test revealed a significant reduction of cardiac output (CO) reserve (CO at peak, 4.5 L/min; CO/Vo2 slope, 4), accounting for moderate-severe reduction of peak oxygen consumption (55% of predicted). Pulmonary artery wedge pressure (PAWP) remained persistently normal both at rest and during exercise, with a near equalization between PAWP and right atrial pressure, consistent with enhanced ventricular interdependence. A diagnosis of pulmonary arterial hypertension associated with systemic sclerosis was formulated, and an oral combination therapy was started with clinical improvement. Nine months later, the patient still complained of dyspnea. This time, echocardiography showed a left atrial dilation of 55 mL/m2 (Figure 1). An invasive cardiopulmonary exercise study was repeated. Mean pulmonary artery pressure was lower and pulmonary vascular resistance halved (3.5 WU) as compared with the previous test. CO was normal at rest, with a supernormal CO reserve (CO/Vo2 slope, 9). PAWP was 12 mm Hg at rest and higher than right atrial pressure. During exercise, tall PAWP V wave appeared, and PAWP rose up to 40 mm Hg (Figure 2). Proper PAWP positioning was confirmed by an oxygen saturation of 95% on blood sampled at the tip of the wedged catheter. Exercise-stress echocardiography excluded dynamic mitral regurgitation. Accordingly, tall V waves were attributed to left ventricular diastolic dysfunction with reduced left atrium compliance.2 Right ventricular pressure overload can enhance ventricular interdependence.3 In our patient, pulmonary arterial hypertension–specific therapy nearly normalized pulmonary vascular resistance and increased CO, thus improving left chamber filling. This hemodynamic effect was particularly evident during exercise, unmasking the presence of exercise-induced pulmonary hypertension due to heart failure with preserved ejection fraction.4,5 Accordingly, further escalation of pulmonary arterial hypertension–specific treatment was avoided. This case highlights the importance of exercise-stress in the catheterization laboratory, not only at the time of the initial diagnosis but also during the follow-up to monitor the possible occurrence of hemodynamic changes in patients with multiple potential confounders and comorbidities, such as patients with systemic sclerosis.