A thirty year-old man with an unknown surgery for congenital heart disease presented with intermittent chest pain and progressive decline in his exercise tolerance. Cardiovascular examination revealed a soft S1, loud S2 without splitting, right ventricular heave, a sustained and laterally displaced apical impulse and clubbing of his fingers. An echocardiogram showed d-transposition of the great arteries (d-TGA), a dilated, sub-pulmonic left ventricle (LV) with reduced function, smaller than expected sub-aortic right ventricle with reduced function, and elevated sub-pulmonic left ventricular systolic pressure without LV outflow tract obstruction. Cardiac MRI revealed d-TGA status post Senning repair, biventricular dysfunction without baffle obstruction, no evidence of repaired atrial or ventricular septal defect or delayed gadolinium enhancement. Cardiac catheterization showed a suprasystemic pulmonary artery pressure, a pulmonary vascular resistance of 18.4 Wood units and a small right to left shunt due to a baffle leak. No coronary disease was found on angiography. The patient was diagnosed with severe pulmonary arterial hypertension and biventricular dysfunction. This pattern of heart failure was discordant from the expected sequelae of palliated congenital heart defects as pulmonary arterial hypertension and LV dysfunction are both uncommon long-term complications after atrial switch. Systematic evaluation for a unifying cause of the patient’s pattern of heart failure was unrevealing until the patient presented with decompensated heart failure and evidence of stimulant withdrawal. Urine toxicology was positive for methamphetamine and the patient was diagnosed with methamphetamine induced pulmonary arterial hypertension and subpulmonic LV dysfunction. This case demonstrates the importance of understanding the common, long-term patterns of heart failure in repaired congenital heart disease and the need to search for alternative etiologies when the pattern is inconsistent. This case further shows the toxic effects of methamphetamine on the pulmonary vasculature and myocardium, which in our patient resulted in a highly unique pattern of sub-pulmonic LV dysfunction and pulmonary arterial hypertension.