Abstract
Myocardial perfusion scintigraphy (MPS) is a valuable diagnostic tool for identifying stable angina and evaluating myocardial viability. In clinical practice, MPS-based analysis tools, such as the Heart Risk View (Nihon Medi-physics Co., Ltd., Tokyo, Japan), have proven effective in assessing left ventricular (LV) dyssynchrony. This case report illustrates the diagnostic utility of MPS in identifying and assessing LV dyssynchrony due to ventricular septal pacing for pacemaker implantation. Upon admission, the patient exhibited symptoms of heart failure (New York Heart Association Class II) due to a Wenckebach-type second-degree atrioventricular block, requiring dual-chamber pacemaker implantation with septal pacing. Eight months postoperatively, phase analysis using the Heart Risk View revealed a significantly reduced ejection fraction (EF: 30 %) and marked LV dyssynchrony [standard deviation width (PhSD): 86 degrees, histogram bandwidth (PhBW): 227 degrees]. Given the presentation of drug-resistant heart failure and asynchronous contraction, a cardiac resynchronization therapy (CRT) device was implanted. Immediately following CRT implantation, phase analysis demonstrated notable improvement in LV function (EF: 42 %) and LV dyssynchronous contraction (PhSD: 30 degrees, PhBW: 110 degrees). LEARNING OBJECTIVE: This study investigated the utility of myocardial perfusion scintigraphy in diagnosing post-implantation dyssynchronous contractions and assessing treatment efficacy. This case underscores the potential for dyssynchrony due to ventricular pacing. It emphasizes the importance of regular reassessment for mechanical dyssynchrony, particularly in patients experiencing a severe decline in ejection fraction or exercise tolerance following pacemaker implantation. Early evaluation is crucial to determine the need for cardiac resynchronization therapy and prevent further deterioration.