Paradoxical septal motion from prior coronary artery bypass graft surgery does not impact left ventricular mechanical dyssynchrony by gated myocardial perfusion imaging

The Postoperative Paradoxical Septum (POPS): A Comprehensive Review on Physio-Pathological Mechanisms

The interventricular septum (IVS) is a core myocardial structure involved in biventricular coupling and performance. Physiologically, during systole, it moves symmetrically toward the center of the left ventricle (LV) and opposite during diastole. Several pathological conditions produce a reversal or paradoxical septal motion, such as after uncomplicated cardiac surgery (CS). The postoperative paradoxical septum (POPS) was observed in a high rate of cases, representing a unicum in the panorama of paradoxical septa as it does not induce significant ventricular morpho-functional alterations nor negative clinical impact. Although it was previously considered a postoperative event, evidence suggests that it might also appear during surgery and gradually resolve over time. The mechanism behind this phenomenon is still debated. In this article, we will provide a comprehensive review of the various theories generated over the past fifty years to explain its pathological basis. Finally, we will attempt to give a heuristic interpretation of the biventricular postoperative motion pattern based on the switch of the ventricular anchor points.

The assessment of left ventricular mechanical dyssynchrony from gated 99mTc-tetrofosmin SPECT and gated 18F-FDG PET by QGS: a comparative study

BACKGROUND

Due to partly conflicting studies, further research is warranted with the QGS software package, with regard to the performance of gated FDG PET phase analysis as compared to gated MPS as well as the establishment of possible cut-off values for FDG PET to define dyssynchrony.

METHODS

Gated MPS and gated FDG PET datasets of 93 patients were analyzed with the QGS software. BW, Phase SD, and Entropy were calculated and compared between the methods. The performance of gated PET to identify dyssynchrony was measured against SPECT as reference standard. ROC analysis was performed to identify the best discriminator of dyssynchrony and to define cut-off values.

RESULTS

BW and Phase SD differed significantly between the SPECT and PET. There was no significant difference in Entropy with a high linear correlation between methods. There was only moderate agreement between SPECT and PET to identify dyssynchrony. Entropy was the best single PET parameter to predict dyssynchrony with a cut-off point at 62%.

CONCLUSION

Gated MPS and gated FDG PET can assess LVMD. The methods cannot be used interchangeably. Establishing reference ranges and cut-off values is difficult due to the lack of an external gold standard. Further prospective research is necessary.

Predictive values of left ventricular mechanical dyssynchrony for CRT response in heart failure patients with different pathophysiology

BACKGROUND

Cardiac resynchronization therapy (CRT) patients with different pathophysiology may influence mechanical dyssynchrony and get different ventricular resynchronization and clinical outcomes.

METHODS

Ninety-two dilated cardiomyopathy (DCM) and fifty ischemic cardiomyopathy (ICM) patients with gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) were included in this retrospective study. Patients were classified based on the concordance between the left ventricular (LV) lead and the latest contraction or relaxation position. If the LV lead was located on or adjacent to both the latest contraction and relaxation position, the patient was categorized into the both match group; if the LV lead was located on or adjacent to the latest contraction or relaxation position, the patient was classified into the one match group; if the LV lead was located on or adjacent to neither the latest contraction nor relaxation position, the patient was categorized to the neither group. CRT response was defined as [Formula: see text] improvement of LV ejection fraction at the 6-month follow-up. Variables with P < .05 in the univariate analysis were included in the stepwise multivariate model.

RESULTS

During the follow-up period, 58.7% (54 of 92) for DCM patients and 54% (27 of 50) for ICM patients were CRT responders. The univariate analysis and stepwise multivariate analysis showed that QRS duration, systolic phase bandwidth (PBW), diastolic PBW, diastolic phase histogram standard deviation (PSD), and left ventricular mechanical dyssynchrony (LVMD) concordance were independent predictors of CRT response in DCM patients; diabetes mellitus and left ventricular end-systolic volume were significantly associated with CRT response in ICM patients. The intra-group comparison revealed that the CRT response rate was significantly different in the both match group of DCM (N = 18, 94%) and ICM (N = 24, 62%) patients (P = .016). However, there was no significant difference between DCM and ICM in the one match and neither group. For the inter-group comparison, Kruskal-Wallis H-test revealed that CRT response was significantly different in all the groups of DCM patients (P < .001), but not in ICM patients (P = .383).

CONCLUSIONS

Compared with ICM patients, systolic PBW, diastolic PBW and PSD have better predictive and prognostic values for the CRT response in DCM patients. Placing the LV lead in or adjacent to the latest contraction and relaxation position can improve the clinical outcomes of DCM patients, but it does not apply to ICM patients.

Myocardial ischemia and previous infarction contribute to left ventricular dyssynchrony in patients with coronary artery disease

AIMS

The aim of this study was to characterize determinants of left ventricular mechanical dyssynchrony (LVMD) in patients with coronary artery disease (CAD).

METHODS

Medical records and results of myocardial perfusion SPECT/CT studies were evaluated in 326 patients with previously diagnosed CAD. LVMD was assessed with the phase analysis of ECG-gated myocardial SPECT. Dyssynchrony was described with phase histogram bandwidth (PHBW), standard deviation (PHSD) or entropy (PHE) values above limit of the highest normal.

RESULTS

Prevalence of LVMD was 29% in CAD patients. Size of the infarction scar and ischemia extent correlated significantly with PHBW, PHSD and PHE (P < 0.001 for all). Independent predictors of LVMD were myocardial infarction scar (P = 0.004), ischemia extent (P = 0.003), and QRS duration (P = 0.003). Previous percutaneous coronary intervention and coronary artery bypass grafting did not independently predict dyssynchrony.

CONCLUSIONS

Almost one-third of CAD patients had significant LVMD. Dyssynchrony was associated with earlier myocardial infarction and presence of myocardial ischemia. Previous percutaneous coronary intervention and coronary artery bypass grafting did not independently predict dyssynchrony.

Phase analysis of gated PET in the evaluation of mechanical ventricular synchrony: A narrative overview

Noninvasive imaging modalities offer the possibility to dynamically evaluate cardiac motion during the cardiac cycle by means of ECG-gated acquisitions. Such motion characterization along with orientation, segmentation preprocessing, and ultimately, phase analysis, can provide quantitative estimates of ventricular mechanical synchrony. Current evidence on the role of mechanical synchrony evaluation is mainly available for echocardiography and gated single-photon emission computed tomography, but less is known about the utilization of gated positron emission tomography (PET). Although data available are sparse, there is indication that mechanical synchrony evaluation can be of diagnostic and prognostic values in patients with known or suspected coronary artery disease-related myocardial ischemia, prediction of response to cardiac resynchronization therapy, and estimation of risk for adverse cardiac events in patients' heart failure. As such, the evaluation of mechanical ventricular synchrony through phase analysis of gated acquisitions represents a value addition to modern cardiac PET imaging modality, which warrants further research and development in the evaluation of patients with cardiovascular disease.

Phase analysis of gated myocardial perfusion single-photon emission computed tomography after coronary artery bypass graft surgery: reflection of late reverse remodeling in patients with patent grafts after coronary artery bypass graft surgery

OBJECTIVE

Phase analysis using gated myocardial perfusion single-photon emission computed tomography (GMPS) is a tool used to assess left ventricular (LV) dyssynchrony. We attempted to investigate the role of LV dyssynchrony assessed by GMPS using phase analysis for the late LV function after coronary artery bypass graft surgery (CABG) in patients with patent grafts.

METHODS

A total of 45 patients who received off-pump CABG with patent graft 1 year after CABG and preserved perfusion reserve were enrolled retrospectively. All patients underwent GMPS before and 3 months and 1 year after CABG. Using the Emory Cardiac Toolbox, both phase histogram bandwidth (PBW) and phase SD derived by phase analysis were used for the analysis, in addition to the conventional perfusion parameters. For the evaluation of LV function, transthoracic echocardiography was also performed.

RESULTS

All of the patients showed perfusion improvement (paired t-test, P<0.05) after CABG. Nonetheless, 30 of 45 patients showed LV dyssynchrony 3 months after CABG. One year after CABG, however, 25 out of 45 patients showed reverse remodeling. Among those patients with reverse remodeling, 19 patients had shown LV 3 months after CABG. Using stepwise logistic regression with forward selection, PBW 3 months after CABG could predict reverse remodeling 1 year after CABG (odds ratio 1.03, P<0.05). Using receiver operating characteristic analysis, PBW 3 months after CABG had the largest area under the curve to detect reverse remodeling 1 year after CABG with a cut-off value of 82 (sensitivity 0.95, specificity 0.56, P<0.001).

CONCLUSION

Postoperative LV dyssynchrony assessed by GMPS using phase analysis may reflect late reverse remodeling and potential of further functional improvement in patients with patent grafts and preserved perfusion reserve after CABG.

Relationship between fragmented QRS and paradoxical septal motion in coronary artery bypass graft patients

OBJECTIVE

Paradoxical septal motion (PSM) can cause confusion in the assessment of ventricular function with scintigraphy even in the absence of ventricular septal damage and ischemia. Fragmented QRS (fQRS) is associated with various cardiac disorders. In this study, we aimed to determine the correlation between paradoxical septal motion and fQRS after coronary artery bypass grafting (CABG).

METHODS

We retrospectively reviewed the hospital records showing scintigraphic images and electrocardiograms (ECG) of the patients who had undergone CABG. The patients were classified based on the evaluation of motion and thickening of the septal wall. The patients with regular thickening of the septal wall and abnormal motion were classified as PSM (+) group. The patients with normal motion and thickening of the septal wall were classified as PSM (-) group. fQRS complexes are defined as various RSR patterns either with or without Q-waves on a 12-lead resting ECG.

RESULTS

PSM was found to be more common in fQRS patients (p < 0.001). PSM was seen in 91.4 % of cases with fQRS and in 79.8 % of cases without fQRS. No significant differences were found in the phase analysis parameters. A correlation was found between septal wall motion values and the presence of fQRS (r = 0.197, p = 0.012).

CONCLUSION

fQRS was associated with PSM. fQRS may cause PSM in patients with CABG without left bundle branch block due to a conduction defect. PSM and fQRS are predictive of cardiac mortality. Patients diagnosed with PSM and fQRS, should be monitored closely.

The assessment of septal wall motion in patients undergoing CABG by myocardial perfusion-gated SPECT

PURPOSE

In this study, we aimed to assess the presence and prevalence of paradoxical septal motion (PSM) by myocardial perfusion-gated single-photon emission computed tomography (SPECT) imaging in patients undergoing coronary artery bypass grafting (CABG).

METHODS

A total of 172 patients (145 men and 27 women, with a mean age of 64.81 ± 8.93 years) undergoing CABG surgery were included in the study. All selected scintigraphic studies of the patients undergoing CABG were reprocessed. Semiquantitative interpretation of septal perfusion, wall motion, and wall thickening was performed with QPS and QGS programs. Phase analysis parameters were also obtained using the Emory Cardiac Toolbox. According to myocardial perfusion-gated SPECT results, the patients were trichotomized as follows: group 1 (nonischemic PSM): regular perfusion and thickening of the septal wall and abnormal motion of the septal wall; group 2 (ischemic PSM): abnormal perfusion, motion, and thickening of the septal wall; group 3 (non-PSM): normal perfusion, motion, and thickening of the septal wall. The data in each of the three groups were compared using Student's t-test and one-way analysis of variance.

RESULTS

No PSM (normal perfusion, motion, and thickening of the septal wall) was observed in 19.2% of patients undergoing CABG, whereas nonischemic PSM (regular perfusion and thickening of the septal wall and abnormal motion of the septal wall) was observed in 60.5% of patients and ischemic PSM (abnormal perfusion, motion and thickening of the septal wall) was seen in 20.3% of patients.

CONCLUSION

According to our study results, PSM is fairly common in patients undergoing CABG. It will be beneficial to use myocardial perfusion scintigraphy-gated SPECT, which is a noninvasive examination method, to identify the presence of PSM and investigate whether it is accompanied by ischemia or infarction.

Left ventricular dyssynchrony assessment using myocardial single-photon emission CT

Myocardial SPECT using standard procedure for perfusion imaging and phase analysis is a novel approach to left ventricular dyssynchrony assessment. Preliminary data suggest excellent repeatability and potential utility for guiding cardiac resynchronization therapy and elucidating mechanisms.

Is off-pump coronary artery bypass surgery superior to on-pump coronary artery bypass surgery on postoperative paradoxical ventricular septal motion?

BACKGROUND

The aims of this study were to investigate the appearance of paradoxical ventricular septal motion (PSM) after coronary artery bypass graft (CABG) surgery and to identify factors that might be related to this abnormality.

METHODS

This prospective study included 119 consecutive patients (38 women, 81 men) who underwent CABG. Patients who underwent on-pump surgery (22 women, 45 men) and patients who underwent off-pump surgery (16 women, 36 men) were studied separately. All subjects underwent preoperative angiographic septal perfusion evaluation, pre- and postoperative echocardiography, and standard electrocardiographic and laboratory investigations, including troponin I and CK-MB levels. Multivariate logistic regression analysis was also performed for a variety of related parameters.

RESULTS

Significant differences in EuroSCORE, length of intensive care unit stay, length of hospital stay, PSM (assessed using echocardiography), septal perfusion (observed using preoperative angiography), postoperative pleural effusion, and intensive care unit recidivism were observed between the two groups (P < .05). Moreover, postoperative PSM was correlated with septal perfusion (r = -0.687**, P < .001), type of operation (r = -0.194*, P = .035), diabetes mellitus (r = 0.273**, P = .003), carotid stenosis (r = 0.235*, P = .011), the number of distal anastomoses (r = 0.245**, P = .008), pleural effusion (r = 0.193*, P = .037), and intensive care unit recidivism (r = 0.249**, P = .007). However, multivariate analysis demonstrated that only preoperative septal perfusion (odds ratio: 0.037; 95% confidence interval: 0.011-0.128; P < .05) constitutes an independent risk factor for PSM (P < .05).

CONCLUSIONS

This study demonstrated that preoperative septal perfusion deficiency represents an independent risk factor for postoperative PSM in patients undergoing CABG. Further investigations addressing the timing of the appearance of PSM and the correlation of this finding with perfusion imaging studies may provide new details concerning the mechanisms that underlie this abnormality.

Prognostic value of left ventricular mechanical dyssynchrony by phase analysis in patients with non-ischemic cardiomyopathy with ejection fraction 35-50% and QRS < 150 ms

BACKGROUND

Left ventricular mechanical dyssynchrony (LVMD) by phase analysis of gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a useful tool for predicting response to cardiac resynchronization therapy and has prognostic value. While most of the studies were done on patients with ischemic cardiomyopathy or those with LV ejection fraction (EF) < 35%, there are little data on the prognostic value of LVMD in patients with non-ischemic cardiomyopathy (NICM), particularly those with mildly decreased systolic function and narrow or intermediate QRS duration.

METHODS AND RESULTS

From the stress SPECT-MPI database at Cleveland Clinic, we identified 324 consecutive patients (mean age 62 ± 13 years, 62% male, 36% diabetics) with NICM, LVEF 35-50% (median [Q1,Q3] 45 [41,49]), and QRS < 150 ms (13% with QRS 120-149 ms). LVMD was determined from gated stress images and expressed as phase standard deviation (SD) and histogram BW (% R-R cycle). For easier graphical illustration, patients were divided into tertiles of LVMD. All-cause death was the primary endpoint and determined using the Social Security Death Index. Cox proportional hazard model was performed to determine the independent predictive value of LVMD, and next Cox models for incremental value. After a mean follow-up time of 1,689 days, 86 (26.5%) of patients died. These patients were older, had more diabetes, more use of diuretics, with wider QRS duration, and with a trend for higher phase SD and BW. After adjusting for age, hypertension, diabetes, aspirin, beta-blockers, diuretics, QRS, and EF, phase SD was an independent predictor of all-cause mortality with hazard ratio [95% CI] 1.97 [1.06,3.66] for the highest tertile, and added incremental prognostic value (P = .025). Similar findings were obtained using histogram BW.

CONCLUSION

In patients with NICM, EF 35-50%, and QRS < 150 ms, increased LVMD on peak stress SPECT was an independent predictor of all-cause mortality. The utility and applicability of such findings in clinical practice need further evaluation in larger and prospective studies.