Left ventricular mechanical dyssynchrony as assessed by phase analysis of ECG-gated SPECT myocardial perfusion imaging

Prognostic significance of phase analysis using SPECT myocardial perfusion imaging in heart failure: a systematic review and meta-analysis

Left ventricular mechanical dyssynchrony (LVMD) is an important prognostic factor for heart failure (HF). Phase analysis of myocardial perfusion SPECT is actively being researched to evaluate LVMD. We performed a systematic review and meta-analysis on the prognostic significance of LVMD using gated SPECT in HF patient. PubMed, Embase, and the Cochrane library were searched until January 10, 2024, for studies reporting the prognostic value of LVMD in HF patients using gated SPECT for outcomes of all-cause death, cardiac death, or major adverse cardiovascular event (MACE). Hazard ratios (HRs) along with their corresponding 95% confidence intervals (CIs) were combined through meta-analysis employing a random-effects model. Funnel plots and Egger's tests were utilized to evaluate publication bias, and trim-and-fill method were applied where bias was identified. Ten studies (2585 patients) were included; six on MACE and five on all-cause or cardiac death. Prognoses were worse in patients with LVMD assessed by SPECT than in those without LVMD, with the overall pooled HR for MACE being 2.05 (95% CI, 1.65-2.54). The pooled HR for all-cause or cardiac death was 2.08 (95% CI, 1.10-3.94); however, publication bias was present (p = 0.0024), and after adjustment, the prognostic value of LVMD was not statistically significant (HR, 1.24; 95% CI, 0.68-2.23). Assessing LVMD through myocardial perfusion SPECT proves to be a significant indicator of subsequent adverse cardiac events in HF patients. Utilizing phase analysis of SPECT could offer valuable insights for risk assessment and decision-making regarding therapy in HF patients.

Clinical impacts of scar reduction on gated myocardial perfusion SPECT after cardiac resynchronization therapy

BACKGROUND

It had not been reported that myocardial scar shown on gated myocardial perfusion SPECT (GMPS) might reduce after cardiac resynchronization therapy (CRT). In this study, we aim to investigate the clinical impact and characteristic of scar reduction (SR) after CRT.

METHODS AND RESULTS

Sixty-one heart failure patients following standard indication for CRT received twice GMPS as pre- and post-CRT evaluations. The patients with an absolute reduction of scar ≥ 10% after CRT were classified as the SR group while the rest were classified as the non-SR group. The SR group (N = 22, 36%) showed more improvement on LV function (∆LVEF: 18.1 ± 12.4 vs 9.4 ± 9.9 %, P = 0.007, ∆ESV: - 91.6 ± 52.6 vs - 38.1 ± 46.5 mL, P < 0.001) and dyssynchrony (ΔPSD: - 26.19 ± 18.42 vs - 5.8 ± 23.0°, P < 0.001, Δ BW: - 128.7 ± 82.8 vs - 25.2 ± 109.0°, P < 0.001) than non-SR group (N = 39, 64%). Multivariate logistic regression analysis showed baseline QRSd (95% CI 1.019-1.100, P = 0.006) and pre-CRT Reduced Wall Thickening (RWT) (95% CI 1.016-1.173, P = 0.028) were independent predictors for the development of SR.

CONCLUSION

More than one third of patients showed SR after CRT who had more post-CRT improvement on LV function and dyssynchrony than those without SR. Wider QRSd and higher RWT before CRT were related to the development of SR after CRT.

Left ventricular mechanical dyssynchrony assessment in long-standing type II diabetes mellitus patients with normal gated SPECT-MPI

BACKGROUND

Assessment of left ventricular mechanical dyssynchrony (LVMD) using phase analysis of gated SPECT-MPI is well established. However, there is little information about the influence of diabetes mellitus on phase analysis. The present work was to evaluate the LVMD in longstanding type II diabetes mellitus (DM) patients with normal gated SPECT-MPI.

METHODS

Retrospective analysis of 146 (86 type II diabetics for > 5 years' duration and 60 nondiabetics) consecutive patients with normal gated SPECT-MPI and adequate LVEF was done. Sixty age- and sex-matched nondiabetic served as control. LVMD was determined from the cutoff values (> mean + 2 SD) observed for phase standard deviation (PSD) and phase bandwidth (PBW) from the control subjects. Multivariate logistic regression analysis was applied to assess the correlation between various confounding factors.

RESULTS

LVMD was detected in 24 (28%) diabetic patients with the pre-defined cut-off values for PSD (> 10.8) and PBW (> 35.6) derived from the controls. Hyperlipidemia, overweight/obesity, duration of DM and its long-term complications were independently associated with LVMD, with long-term complications being the highest risk factor (OR 28.00; P < .001).

CONCLUSION

The evolution time of the patients with type II diabetes mellitus affects the left ventricular mechanical synchrony.

Reference values for left ventricular systolic synchrony according to phase analysis of ECG-gated myocardial perfusion SPECT

BACKGROUND

The aim of this study was to define reference values for left ventricular systolic synchrony and for the volume parameters of the left ventricle using myocardial perfusion SPECT-derived phase analysis method.

METHODS

We evaluated data of 433 patients who underwent myocardial perfusion SPECT/CT during January 2012-February 2013 in Kuopio University Hospital. The final study population consisted of 52 patients (aged 42-84 years) who met the criteria: (1) no previously diagnosed cardiac disease, (2) normal ECG at rest, (3) no advanced coronary artery disease in CT and 4) normal myocardial perfusion in stress/rest myocardial perfusion SPECT/CT. The severity of mechanical dyssynchrony was assessed by phase analysis of gated myocardial SPECT at stress stage after pharmacological exercise and at rest using Quantitative Gated SPECT (QGS) software. Volume parameters of the left ventricle were also assessed.

RESULTS

The phase histogram bandwidth at rest was 28.0 [63.7] degrees (median [95th percentile]). The standard deviation of phase histogram at rest was 7.8 [26.5] degrees. Entropy at the rest study was 54.0 [63.7] %. All left ventricular dyssynchrony parameters were statistically significantly higher at stress compared to rest. There were no statistically significant differences in dyssynchrony values between men and women. In volume parameters, reference values in male were expectedly higher than in female. Cardiac output did not differ significantly between genders.

CONCLUSION

In subjects without signs of cardiac diseases, the left ventricular systolic function is well synchronized. Phase analysis measurement does not depend on gender, age, BMI or blood pressure, but the values of dyssynchrony parameters increase during pharmacological stress.

Cut-off values of myocardial perfusion gated-SPECT phase analysis parameters of normal subjects, and conduction and mechanical cardiac diseases

BACKGROUND

The aim of this study was to determine the cut-off values of gated myocardial perfusion rest SPECT phase analysis parameters of normal subjects, and conduction (CCD) and mechanical cardiac diseases (MCD).

METHODS

We prospectively analyzed 455 patients by means of phase analysis using SyncTool™ (Emory Cardiac Toolbox™). Of these, 150 corresponded to the control group (group 1, normal subjects) and 305 corresponded to patients with cardiac diseases (group 2, 63 with only CCD, 121 with only MCD, and 121 with CCD plus MCD). The optimal cut-off (CO) values of the peak phase (P), standard deviation (SD), bandwidth (B), skewness (S), and kurtosis (K) for discriminating between normal and dyssynchrony were obtained.

RESULTS

In order to differentiate group 1 from group 2, CO of SD > 18.4 and CO of B > 51 were the most sensitive parameters (75.7%, 95% CI 70.5%-80.4%, and 78.7%, 95% CI 73.7%-83.1%, respectively), and CO of S ≤ 3.2 and CO of K ≤ 9.3 were the most specific (92%, 95% CI 86.4%-95.8%, and 94.7%, 95% CI 89.8%-97.7%, respectively). In order to differentiate patients with CCD and MCD, CO values were SD > 26.1, B > 70, S ≤ 2.89, and K ≤ 10.2. In order to differentiate between patients with (n: 26) and without (n: 216) criteria of cardiac resynchronization therapy, CO values were SD > 40.2, B > 132, S ≤ 2.3, and K ≤ 4.6.

CONCLUSIONS

In this pilot study, different CO values of phase histogram parameters were observed between normal subjects and patients with conduction and MCD, and between patients with and without criteria of cardiac resynchronization therapy.

Cardiac function changes with switching from the supine to prone position: analysis by quantitative semiconductor gated single-photon emission computed tomography

BACKGROUND

Prone positioning is required in certain operations such as spinal surgery. Changes in cardiac function in the prone position have been studied with various methodologies. Few studies have investigated changes in left ventricular diastolic function and rhythm in subjects turned prone.

METHODS AND RESULTS

Cardiac function was evaluated in the supine and prone positions in 90 patients without atrial fibrillation who underwent (99m)Tc-tetrofosmin quantitative gated single-photon emission computed tomography. Three groups of 30 patients each were classified as "no history of myocardial ischemia or cardiomyopathy" (Group A), "history of myocardial infarction" (Group B), and "ischemic heart disease without myocardial infarction history" (Group C). Upon assuming the prone position, the cardiac index and any dyssynchrony worsened in all groups. Ejection fraction changes occurred only in Group B, and diastolic function changes occurred in Groups B and C, but not in Group A. The changes caused by prone positioning were more severe in the patients with poor cardiac function.

CONCLUSIONS

Prone positioning induces significant changes in systolic and diastolic function, as well as dyssynchrony. The negative effects of prone positioning are more severe in patients with poor baseline cardiac function.

Deterioration of left ventricular ejection fraction and contraction synchrony during right ventricular pacing in patients with left bundle branch block

BACKGROUND

Electrocardiographic left bundle branch block (LBBB) may be intrinsic, due to ventricular conduction system disease, or induced by right ventricular pacing. Prior reports clearly delineate the derogatory impact of LBBB on left ventricular (LV) mechanical synchrony and global function, and suggest that the intrinsic and induced varieties are equivalent. This study sought to determine the difference in LV synchrony and global function between intrinsic LBBB and right ventricular apical pacing induced LBBB.

METHODS

Ten patients with heart failure, diminished ejection fraction (EF) (33 ± 11%), intrinsic LBBB and an implanted cardiac pacing device were studied. In each patient, separate gated SPECT acquisitions were performed during intrinsic ventricular activation (atrial pacing) and during induced LBBB (atrial and right ventricular pacing). During each condition, LVEF, contraction synchrony (phase standard deviation, PSD), and spatial pattern of activation were measured.

RESULTS

Compared to intrinsic, induced LBBB was associated with decreased EF (30 ± 11% vs 33 ± 11%, P = .007), contraction synchrony (PSD 49.7 ± 23.2° vs 41.6 ± 19.8, P = .02), and a disparate spatial pattern of activation.

CONCLUSIONS

Induced LBBB is associated with significantly worse global and regional LV mechanical function than intrinsic LBBB.

Left ventricular mechanical dyssynchrony in patients with impaired left ventricular function undergoing gated SPECT myocardial perfusion imaging

INTRODUCTION

Gated SPECT myocardial perfusion imaging (MPI) has been used to quantify mechanical dyssynchrony. Mechanical dyssynchrony appears to be related to response to cardiac resynchronization therapy.

OBJECTIVE

To evaluate the presence and predictors of mechanical dyssynchrony in patients with impaired left ventricular function (LVEF) ≤50%.

METHODS

The study included 143 consecutive patients referred for gated SPECT MPI with LVEF ≤50%. Gated SPECT MPI was performed according to a stress/rest protocol acquiring images with Tc 99m-tetrofosmin. Emory Cardiac Toolbox software was used for phase analysis and a standard deviation (SD) ≥43° was considered to indicate mechanical dyssynchrony.

RESULTS

Mechanical dyssynchrony was present in 53.1% of the patients. Its predictors were diabetes (OR 2.0, p≤0.05), summed stress score (OR 1.1, p≤0.0005), summed rest score (OR 1.1, p≤0.0001), end-diastolic volume (OR 1.0, p≤0.0001), LVEF (OR 0.9, p≤0.0001), LVEF ≤35% (OR 3.1, p≤0.005) and LVEF ≤35% and QRS ≥120 ms (OR 3.5, p≤0.05). In this study QRS width and QRS ≥120 ms were not predictors of mechanical dyssynchrony.

CONCLUSIONS

Myocardial perfusion imaging can be used to assess mechanical dyssynchrony. In patients with impaired ventricular function mechanical dyssynchrony was highly prevalent and was related to parameters of left ventricular function and perfusion.

Phase analysis in patients with reversible perfusion defects and normal coronary arteries at angiography

OBJECTIVE

A count-based new technique from gated myocardial perfusion single-photon emission tomography (gMPS) was developed to allow the phase analysis providing information about the left ventricular (LV) regional discordance in contractility which is a measure of LV dyssynchrony. Since the phase analysis provides data for evaluating the dyssynchronous LV contraction, it has an important role in diagnosis and management of patients with left ventricular dysfunction. The aim of the study was to assess the presence of left ventricular dyssynchrony in patients with reversible perfusion defects on gMPS scans and normal or near normal coronary arteries at angiography.

METHODS

32 patients (19 men, 59 %) with reversible mild perfusion defects on gMPS and normal coronary angiogram were retrospectively enrolled in the study. The peak of the phase histogram, the standard deviation of the phase distribution (PSD), the width of the band (PHB), and the symmetry and peakedness of the phase histogram, which are the assessment parameters for the LV dyssynchrony, were calculated from gMPS scans of patients by means of the phase analysis.

RESULTS

Although, five quantitative variables are derived from the phase analysis of gMPS, PSD and PHB are two quantitative indices to assess LV global mechanical dyssynchrony and measurements of PSD (men 24.96 ± 7.31, women 24.26 ± 10.07) and PHB (men 70.1 ± 13.99, women 71.0 ± 30.4) were significantly higher than the those reported in the literature (p < 0.001). No significant differences in gMPS phase analysis indices were found between both sexes except kurtosis.

CONCLUSION

As a conclusion, this study provides the phase analysis to detect LV mechanical dyssynchrony as new evidence supporting the concept that an abnormal scintigraphy finding, rather than being false-positive, may be an early marker of vasomotion changes associated with occult atherosclerosis in patients with normal coronary angiography findings.

Ventricular dyssynchrony assessed by gated myocardial perfusion SPECT using a geometrical approach: a feasibility study

PURPOSE

Left ventricular dyssynchrony may predict response to cardiac resynchronization therapy and may well predict adverse cardiac events. Recently, a geometrical approach for dyssynchrony analysis of myocardial perfusion scintigraphy (MPS) was introduced. In this study the feasibility of this geometrical method to detect dyssynchrony was assessed in a population with a normal MPS and in patients with documented ventricular dyssynchrony.

METHODS

For the normal population 80 patients (40 men and 40 women) with normal perfusion (summed stress score ≤2 and summed rest score ≤2) and function (left ventricular ejection fraction 55-80%) on MPS were selected; 24 heart failure patients with proven dyssynchrony on MRI were selected for comparison. All patients underwent a 2-day stress/rest MPS protocol. Perfusion, function and dyssynchrony parameters were obtained by the Corridor4DM software package (Version 6.1).

RESULTS

For the normal population time to peak motion was 42.8 ± 5.1% RR cycle, SD of time to peak motion was 3.5 ± 1.4% RR cycle and bandwidth was 18.2 ± 6.0% RR cycle. No significant gender-related differences or differences between rest and post-stress acquisition were found for the dyssynchrony parameters. Discrepancies between the normal and abnormal populations were most profound for the mean wall motion (p value <0.001), SD of time to peak motion (p value <0.001) and bandwidth (p value <0.001).

CONCLUSION

It is feasible to quantify ventricular dyssynchrony in MPS using the geometrical approach as implemented by Corridor4DM.

Relationship of technetium-99m tetrofosmin-gated rest single-photon emission computed tomography myocardial perfusion imaging to death and hospitalization in heart failure patients: results from the nuclear ancillary study of the HF-ACTION trial

BACKGROUND

We hypothesized that the severity of resting perfusion abnormalities assessed by the summed rest score (SRS) would be associated with a higher rate of adverse outcomes in patients with heart failure (HF) and reduced left ventricular (LV) ejection fraction (EF).

METHODS

A subset of 240 subjects from HF-ACTION underwent resting technetium-99m tetrofosmin-gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Images were evaluated using a 17-segment model to derive the SRS and additional nuclear variables.

RESULTS

After adjusting for prespecified covariates, SRS was significantly associated with the primary end point (hazard ratio 0.98, 95% confidence interval [CI] 0.97-1.00, P = .04), with a higher SRS corresponding to lower risk of an event. This association was not present in the unadjusted analysis. The relationship between SRS and the primary outcome was likely due to a higher event ratein patients with ischemic HF and a low SRS. The LV phase SD was not predictive of the primary outcome (hazard ratio 1.00, 95% confidence interval 0.99-1.01, P = .49). In a post hoc analysis, nuclear variables provided incremental prognostic information when added to clinical information (P = .006).

CONCLUSIONS

Gated SPECT MPI provides important information in patients with HF and reduced LVEF. In the adjusted analysis, SRS has an unexpected relationship with the primary end point. Phase SD was not associated with the primary end point. Rest-gated SPECT MPI provides incrementally greater prognostic information than clinical information alone.

Quantification of ventricular resynchronization reserve by radionuclide phase analysis in heart failure patients: a prospective long-term study

BACKGROUND

Phase analysis, developed to assess dyssynchrony from ECG-gated radionuclide ventriculography, has shown promising results. We hypothesized that quantifying the cardiac resynchronization reserve, that is, the extent of response to cardiac resynchronization therapy (CRT), by radionuclide imaging could potentially identify patients who are best suited for CRT.

METHODS AND RESULTS

Seventy-four patients ages 64.8±10.1 years were prospectively studied from July 2004 to July 2006, of whom 62.2% and 37.8%, respectively, were in New York Heart Association class 3 and 4. Mean QRS width was 173±25 ms. ECG-gated radionuclide ventriculography to quantify interventricular and intraventricular dyssynchrony was performed at baseline with and without CRT and at the 3-month follow-up visit. Amino-terminal-pro-brain natriuretic peptide (NT-pro-BNP) levels were also determined at baseline and at 3 months. During a mean follow-up of 10.1±7.6 months, there were 37 (50%) clinical events that defined the nonresponder group, including cardiac death or readmission for worsening heart failure. In multivariate Cox model analysis, higher NT-pro-BNP blood levels were associated with a significant increase in the risk for event (hazard ratio=1.085 for a 100 pg/L increase in NT-pro-BNP; 95% confidence interval, 1.014 to 1.161). Each 10° elevation in intraventricular dyssynchrony was associated with a decrease in the risk of events (hazard ratio=0.456, 95% confidence interval, 0.304 to 0.683). Receiver operating characteristic curve analysis demonstrated that an interventricular dyssynchrony cutoff value of 25.5° for intraventricular synchrony yielded 91.4% sensitivity and 84.4% specificity for predicting a good response to CRT.

CONCLUSIONS

The quantification of interventricular dyssynchrony with radionuclide phase analysis suggests that early postimplantation interventricular dyssynchrony may provide identification of CRT responders.

Myocardial perfusion, function, and dyssynchrony in patients with heart failure: baseline results from the single-photon emission computed tomography imaging ancillary study of the Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing (HF-ACTION) Trial

BACKGROUND

There are currently limited data on the relationships between resting perfusion abnormalities, left ventricular ejection fraction (LVEF), New York Heart Association (NYHA) functional class, and exercise capacity as defined by peak VO(2) and 6-minute walk test in patients with heart failure (HF) and reduced LVEF. Furthermore, the association between resting perfusion abnormalities and left ventricular dyssynchrony is currently unknown. This article addresses the Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing (HF-ACTION) gated SPECT imaging (gSPECT) substudy baseline results.

METHODS

HF-ACTION was a multicenter, randomized controlled trial of aerobic exercise training versus usual care in 2,331 stable patients with LVEF of < or = 35% and NYHA class II to IV HF symptoms treated with optimal medical therapy. Subjects enrolled in the HF-ACTION substudy underwent resting Tc-99m tetrofosmin gSPECT at baseline (n = 240). Images were evaluated for extent and severity of perfusion abnormalities using a 17-segment and a 5-degree gradation severity score (summed rest score [SRS]). Left ventricular function and dyssynchrony were assessed using validated available commercial software.

RESULTS

The average age of patients enrolled was 59, 69% were male, 63% were white, and 33% were African American. Of the 240 participants, 129 (54%) were ischemic and 111 (46%) were nonischemic in etiology. The median LVEF by gSPECT for the entire cohort was 26%. Among the nuclear variables, there was a modest correlation between LVEF and SRS (r = -0.31, P < .0001) and there were stronger correlations between phase SD and SRS (r = 0.66, P < .0001) as well as phase SD and LVEF (r = -0.50, P < .0001). Patients with NYHA class III symptoms had more severe and significant degrees of dyssynchrony (median phase SD 54 degrees ) than those with NYHA class II symptoms (median phase SD 39 degrees, P = .001). Patients with an ischemic etiology had a higher SRS (P < .0001) and significantly more dyssynchrony (P < .0001) than those who were nonischemic. However, there was no difference in LVEF or objective measures of exercise capacity between these groups. With respect to peak VO(2), there was a weak correlation with LVEF (r = 0.18, P = .006) and no correlation with SRS (r = -0.04, P = 0.59) or with dyssynchrony (r = -0.13, P = .09). A weak but statistically significant correlation between SRS and 6-minute walk was observed (r = -0.15, P = .047).

CONCLUSIONS

Gated SPECT imaging can provide important information in patients with HF due to severe LV dysfunction including quantitative measures of global systolic function, perfusion, and dyssynchrony. These measurements are modestly but significantly related to symptom severity and objective measures of exercise capacity.

Radionuclide imaging in ischaemic heart failure

INTRODUCTION OR BACKGROUND

Many tests are available for the investigation of patients with heart failure. The identification of the underlying aetiology of ventricular dysfunction is crucial as early treatment may limit or even reverse myocardial abnormalities.

SOURCES OF DATA

This article describes cardiac radionuclide imaging techniques and their applications in ischaemic ventricular dysfunction. Evidence for the role of these techniques is summarized with particular reference to current guidelines.

AREAS OF AGREEMENT

Both positron emission tomography (PET) and single photon emission computed tomography (SPECT) techniques are widely validated for the detection of myocardial viability and their use is recommended in both national and international guidelines.

AREAS OF CONTROVERSY

Although assessments of ventricular phase and myocardial innervation hold promise for the stratification of patients to cardiac resynchronization therapy, the poor performance of echocardiographic predictors of response in the recently published PROSPECT trial suggest that these techniques face a tough challenge.

GROWING POINTS

The use of integrated multimodality imaging techniques such as PET/computed tomography to assess for ischaemic causes of left ventricular dysfunction is an area that is currently under investigation, as is the role of nuclear techniques in the assessment of stem cell retention, distribution and function when used in patients with heart failure.

AREAS TIMELY FOR DEVELOPING RESEARCH

Ongoing developments in radionuclide molecular imaging for assessment of angiogenesis, apoptosis and interstitial alterations during cardiac remodeling may have important implications for the prognosis and treatment of patients with heart failure.