A man in his early 70s with a history of permanent atrial fibrillation treated with atrioventricular junction ablation and biventricular pacemaker implantation was hospitalized with decompensated heart failure and acute kidney injury. His history was notable for nonischemic cardiomyopathy with ejection fraction of 40% and idiopathic pulmonary fibrosis, for which he underwent single-lung transplant 9 years prior. Following diuresis and medical optimization, repeated echocardiogram showed a newly depressed ejection fraction (30%). His electrocardiogram (ECG) was notable for alternating QRS morphologies (Figure 1A). The left ventricular (LV) pacing vector was programmed from LV tip to right ventricular (RV) lead ring. During pacemaker threshold testing, a change in QRS morphology was observed as the output was reduced (Figure 1B). Chest radiography revealed severe right pulmonary fibrosis leading to ipsilateral mediastinal shift and pacemaker lead position unchanged from implantation.
Guandalini GS, Hyman MC. Worsening Cardiomyopathy Despite Biventricular Pacing. JAMA Cardiol. 2021;6(11):1338–1339. doi:10.1001/jamacardio.2021.2755
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