Original ArticleClinical impacts of scar reduction on gated myocardial perfusion SPECT after cardiac resynchronization therapy
Introduction
Cardiac resynchronization therapy (CRT) improves survival and cardiac functions in patients with advanced heart failure (HF) and wide QRS duration (QRSd), as a pacemaker alone (CRT-P) or in combination with a cardioverter defibrillator (CRT-D). About 30% of the patients, who met the standard indications and received CRT, did not show any benefit after CRT.1, 2, 3 Studies have demonstrated that a higher scar burden has a negative impact and may inhibit the CRT response.4, 5, 6, 7
Gated myocardial perfusion SPECT (GMPS) with phase analysis provides comprehensive assessments of myocardial substrates, including LV volume and function, scar burden, myocardial wall thickening, and mechanical dyssynchrony.8, 9, 10, 11, 12 In this study, we firstly described the occurrence of scar reduction (SR) on post-CRT GMPS. In addition, the clinical impact and characteristics were assessed.
Section snippets
Study Population
Sixty-one patients were retrospectively enrolled in this study according to the following criteria: (a) symptomatic HF with New York Heart Association (NYHA) class III-IV, despite optimal medical treatment (ACE inhibitors, ß-blockers, spironolactone, and furosemide) and optimized revascularization of coronary artery; (b) sinus rhythm with LBBB configuration defined as a wide QRSd (≥ 120 ms) with rS or QS morphology at V1-V2 precordial leads in the baseline electrocardiography (ECG); and (c)
Clinical Impacts and Characteristics of Scar Reduction
As shown in Table 1, 22 of the 61 patients (36%) developed SR after CRT, and the SR group had more MRR than the non-SR group (39 patients, 64%) although the P value was not significant. For baseline characteristics, the SR group had younger age, longer QRSd, more scar and more RWT than the non-SR group. Otherwise, no significant difference was noted for the other baseline characteristics between the two groups of patients.
As shown in Table 2, the SR group showed significantly more improvement
Major Findings
In our study, significant reduction of scar burden on GMPS was found in about one third of HF patients after CRT. The patients with SR had more improvements in myocardial function and LV mechanical dyssynchrony on GMPS. Wider QRS duration (≥ 162 ms) and more RWT (≥ 70.3%) were significant predictors for the development of SR after CRT.
Scar Reduction on GPMS After CRT
To the best of our knowledge, this paper should be the first report about scar reduction on GMPS after CRT. Since CRT itself provides no direct effect on
Conclusion
In our study, more than one third of heart failure patients following standard indication for CRT developed SR on post-CRT GMPS. The baseline QRSd on ECG (> 162 ms) and RWT on GMPS (> 70.3%) were independent predictors for the development of SR after CRT implantation.
New Knowledge Gained
Our study suggests that CRT not only enables more synchronous contraction of heart but also may enhance scar reduction shown on MPI, possibly mediated by regeneration of hibernated myocardium. Further studies are needed for clarifying the issues inspired by our study.
Disclosures
This study was supported by a Grant from the Taiwan Ministry of Science and Technology (Project Number: 107-2314-B-758-001-MY3, PI: Guang-Uei Hung) and Taichung Veterans General Hospital (Project Number: TCVGH-1093103C, TCVGH-1083104C, TCVGH-1073104C, PI: Jin-Long Huang). This research was also supported in part by a grant from the American Heart Association (Project Number: 17AIREA33700016, PI: Weihua Zhou) and a new faculty startup grant from Michigan Technological University Institute of
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Chi-Yen Wang, Guang-Uei Hung, and Hsu-Chung Lo are listed as the first authors who contributed equally to this work.
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