A 68-year-old male with a history of severe COPD presents to the emergency department with acute onset dyspnea, tachypnea, peripheral edema, and jugular venous distention. He reports worsening fatigue and shortness of breath over several weeks, now occurring at rest. Physical exam reveals cyanosis, a loud P2 heart sound, and hepatomegaly. An echocardiogram demonstrates right ventricular dilation with right ventricular hypertrophy and reduced right ventricular systolic function. Which of the following is the most likely diagnosis?