ABC | Volume 111, Nº4, Octuber 2018

Original Article Nascimento et al Electromechanical dyssynchrony and GATED SPECT in CRT Arq Bras Cardiol. 2018; 111(4):607-615 Figure 1 – Comparison of the mean score of the Minnesota Living with Heart Failure Questionnaire before and after cardiac resynchronization therapy, using Student t test. 70 60 50 40 30 20 10 0 66 ± 14 31 ± 17 Q. Minnessota PRE Q. Minnessota POS dyssynchrony do not respond to CRT on GATED SPECT because they have no change suggestive of mechanical dyssynchrony on baseline tests. Likewise, patients with severe mechanical dyssynchrony and changes on baseline tests show a marked improvement in the GATED SPECT parameters after CRT, mainly HBW. Of the group of responders, 77.7% had the pacing lead implanted in the lateral region, 11.1% in the posterolateral region, and 11.1% in the posteroseptal region (Figure 6). When assessing synchronism by use of myocardial perfusion imaging, concordant LV lead positioning was achieved in 54% of the cases (Figure 7 illustrates a concordant implantation), the major reason for not reaching concordance being the anatomical variability of the veins related to coronary sinus, as well as the absence of tributaries reaching the site determined by myocardial perfusion imaging. One of the patients had an aneurysmal coronary sinus, which prevented the lead from being anchored. Thus, the LV lead implantation was converted to the epicardial pathway, in the maximally delayed site. Discussion In our study, we observed that CRT led to patients’ clinical improvement and to a reduction in electrical and mechanical dyssynchrony. Although CRT is associatedwith the improvement of several clinical parameters, not every patient benefited from that, and longer QRS duration on the electrocardiogram and increased SD and HBW on GATED SPECT were markers of higher likelihood of clinical response. In addition, we observed that GATED SPECT could identify the last myocardial segment to contract, the ideal LV lead implantation site on CRT. However, because of anatomical limitations, that identification led to concordant implantation in only 54% of the cases. Table 1 – General baseline characteristics of the patients submitted to cardiac resynchronization device implantation Demographic characteristics N or mean ± SD Total of patients 15 Age (years) 63.21 ± 7.7 Body mass index (kg/m 2 ) 26.92 ± 5.4 Male sex 4 Diabetes mellitus 6 Hypertension 9 Dyslipidemia 8 Smoking 0 Previous coronary artery disease 7 Previous infarction 7 Coronary artery bypass grafting 2 Percutaneous coronary intervention 0 NYHA functional class II 1 NYHA functional class III 7 NYHA functional class IV 5 Beta-blocker 13 Angiotensin-converting-enzyme inhibitor 8 Angiotensin-receptor blocker 7 Acetylsalicylic acid 2 Diuretics 8 Statin 5 Aldosterone antagonist 8 Digoxin 4 609