Coronary Flow Reserve Predicts Longitudinal Myocardial Deformation Capacity in Heart-Transplanted Patients

Radial artery intima-media thickening is a sensitive marker of atherosclerosis and coronary artery stenosis, a lesson from a 6-year study of a spontaneous monkey model

Atherosclerosis is the primary driver of cardiovascular and cerebral vascular diseases globally. Atherosclerotic plaques have been detected in multiple arterial locations, such as the aorta, carotids, and coronaries. However, it remains uncertain if there are variations in susceptibility and association among arteries of different calibers. Utilizing a spontaneous rhesus monkey model of metabolic syndrome (MetS), we assessed the susceptibility of atherosclerosis among the radial artery, femoral artery, and carotid artery and their correlation with coronary heart disease (CHD). The development of atherosclerosis in the three arteries mentioned above was evaluated by Intima-media thickness (IMT) and plaques using echo imaging over 6 years in a cohort of elderly monkeys with metabolic disorders. Coronary artery stenosis was assessed by coronary flow reserve (CFR) simultaneously. The diagnosis was further confirmed by histopathological examination, and RNA sequencing was employed to probe the transcriptional underpinnings of atherosclerotic development. The spontaneous development of atherosclerosis was observed in elderly monkeys, and the incidence of atherosclerosis was increased by three times in the MetS monkeys compared to the age-matched control group. During the 6-year follow-up, there was a notable increase in the IMT across all three arteries, with the radial artery showing the most pronounced thickening. Moreover, only the radial IMT correlated with CFR, suggesting its potential as a non-invasive diagnostic indicator for CHD. Histopathology confirmed the findings by echo imaging and identified different extracellular matrix (ECM) remodeling patterns in the arteries. In addition, transcriptomic analysis revealed that ECM remodeling and inflammation-related pathways were significantly upregulated in radial atherosclerotic samples, multiple inflammatory pathways were upregulated in the femoral lesion samples, and the carotid samples failed to enrich any pathways due to a lack of differentially expressed genes compared to the control samples. Non-human primates, which share extensive genetic and physiological similarities with humans, develop atherosclerosis spontaneously. This provides an invaluable platform for investigating the intricate mechanisms of arterial disease and evaluating potential treatments. Using the monkey model, we identified the radial artery as a sensitive indicator for assessing the occurrence and progression of atherosclerosis and coronary stenosis.

Extent of coronary atherosclerosis is associated with deterioration of left ventricular global longitudinal strain in patients with preserved ejection fraction undergoing coronary computed tomography angiography

Background

This study aimed to investigate the association between the extent and severity of coronary atherosclerosis, epicardial adipose tissue (EAT) accumulation, and left ventricular (LV) global longitudinal strain (GLS) in patients with preserved LV ejection fraction (LVEF) and without LV regional wall motion abnormalities.

Methods

This study included 169 preserved LVEF patients without LV wall motion abnormalities who underwent coronary computed tomography (CT) angiography for the assessment of suspected coronary artery disease (CAD). The segment stenosis score (SSS) and segment involvement score (SIS) were calculated to evaluate CAD extent. The EAT volume was defined as CT attenuation values ranging from -250 to -30 HU within the pericardial sac. LVGLS was measured using echocardiography to assess subclinical LV dysfunction.

Results

All patients had preserved LVEF of ≥50%, and the mean LVGLS was -18.7% (-20.5% to -16.9%). Mean SSS and SIS were 2.0 (0-5) and 4.0 (0-36), respectively, while mean EAT volume was 116.1 mL (22.9-282.5 mL). Multivariate analysis using linear regression model demonstrated that LVEF (β, -17.0; 95% CI, -20.9 - -13.1), LV mass index (β, 0.03; 95% CI, 0.01-0.06), and EAT volume (β, 0.010; 95% CI, 0.0020-0.0195) were independently associated with LVGLS; however, obstructive CAD was not. The multivariate models demonstrated that SSS (Î, 0.12; 95% CI, 0.05-0.18) and SIS (Î, 0.27; 95% CI, 0.10-0.44) were correlated with deterioration of LVGLS, independent of other parameters.

Conclusion

This study demonstrates that EAT volume and CAD extent are associated with the deterioration of LVGLS in this population.

Reduction in myocardial function and oxygen consumption after chemoradiotherapy in patients with esophageal cancer

BACKGROUND

Chemoradiotherapy (CRT) may induce myocardial dysfunction, congestive heart failure, and impaired physical performance in patients with esophageal cancer (EC). We aimed to investigate left ventricular (LV) function at rest and during stress, using echocardiography (echo) and a cardiopulmonary exercise (CPX) test both before and immediately after completing CRT.

MATERIAL AND METHODS

Consecutive EC patients referred for curative treatment were enrolled. Patients attended either definitive CRT or neoadjuvant CRT with subsequent surgery. The evaluation included cardiac biomarkers, electrocardiogram, echo, and CPX test. The primary endpoint was changes in left ventricular (LV) global longitudinal strain (GLS) at rest. Secondary endpoints were LV ejection fraction (LVEF), LV diastolic function, LVEF and GLS at peak exercise, and maximal oxygen consumption (VO_2max). The trial was registered with ClinicalTrials.gov (NCT03619317).

RESULTS

Among 47 patients enrolled (94% male; median age 67 years, range 50-86 years), cardiac examinations were performed a median of three days [Interquartile range (IQR (1-5))] before CRT and one day [IQR (0-6)] after CRT. At rest, GLS and LVEF decreased, 17.6 vs. 16.4% and 56.4 vs. 55.1%, respectively (p = 0.004; p = 0.030). Furthermore, an absolute decrease of at least 5% in LVEF and 2.5% in GLS was noted in 21% of the patients. Signs of LV diastolic dysfunction increased from 13 to 21% (p = ns). VO_2max significantly decreased; 21.2 ml/kg/min vs. 18.8 ml/kg/min (p < 0.001).

CONCLUSION

LV function and physical performance decreased in EC patients after CRT, and the LV systolic reserve capacity declined. This study highlighted that EC treatment was associated with early cardiac side effects, which may have clinical and prognostic implications.

The role of non-invasive imaging modalities in cardiac allograft vasculopathy: an updated focus on current evidences

Cardiac allograft vasculopathy (CAV) is an obliterative and diffuse form of vasculopathy affecting almost 50% of patients after 10 years from heart transplant and represents the most common cause of long-term cardiovascular mortality among heart transplant recipients. The gold standard diagnostic technique is still invasive coronary angiography, which however holds potential for complications, especially contrast-related kidney injury and procedure-related vascular lesions. Non-invasive and contrast-sparing imaging techniques have been advocated and investigated over the past decades, in order to identify those that could replace coronary angiography or at least reach comparable accuracy in CAV detection. In addition, they could help the clinician in defining optimal timing for invasive testing. This review attempts to examine the currently available non-invasive imaging techniques that may be used in the follow-up of heart transplant patients, spanning from echocardiography to nuclear imaging, cardiac magnetic resonance and cardiac computed tomography angiography, weighting their advantages and disadvantages.

Coronary Flow Velocity Reserve and Myocardial Deformation Predict Long-Term Outcomes in Heart Transplant Recipients

BACKGROUND

After heart transplantation (HTx), invasive coronary angiography is the gold standard for surveillance of cardiac allograft vasculopathy (CAV). Noninvasive CAV surveillance is desirable. The authors examined left ventricular global longitudinal strain (LVGLS) and noninvasive coronary flow velocity reserve (CFVR) related to CAV and prognosis after HTx.

METHODS

Doppler echocardiographic CFVR and LVGLS were evaluated in 98 HTx patients. All-cause mortality and major adverse cardiac events (MACE), including hospitalization for heart failure, cardiovascular death, and significant CAV progression, were recorded.

RESULTS

Median follow-up duration was 3.3 years (range: 1.7-5.4 years). Patients with low CFVR (<2.0; n = 20) showed reduced MACE-free survival (hazard ratio, 4.3; 95% CI, 2.2-8.4; P < .0001) and increased all-cause mortality (hazard ratio: 4.7; 95% CI: 2.0-11.3; P < .0001) compared with patients with high CFVR (≥2.0; n = 78). Worsened LVGLS (≥-15.5%) was also a strong independent predictor of MACE and cardiovascular and all-cause mortality. Combined low CFVR and worsened LVGLS provided incremental prognostic value, even after adjustment for CAV and time since HTx. The prevalence of low CFVR increased significantly with CAV severity, and the prevalence of combined low CFVR and/or worsened LVGLS was high in patients with moderate CAV (86%) and those with severe CAV (83%). The negative predictive value of combined high CFVR and improved LVGLS to rule out significant CAV was 94.5% (95% CI, 86.2%-98.4%), whereas the positive predictive value was 39.0% (95% CI, 25.3%-54.3%). The model had sensitivity of 84.2% (95% CI, 63.6%-95.3%) and specificity of 67.5% (95% CI, 56.6%-77.2%) for one or more abnormal parameters.

CONCLUSIONS

In HTx patients with severe CAV, a higher prevalence of low CFVR and worsened LVGLS was observed. Both measurements were strong independent predictors of MACE and all-cause mortality in HTx patients. Combined CFVR and LVGLS provided incremental prognostic value and showed an excellent ability to rule out significant CAV and may be considered as part of routine CAV surveillance of HTx patients.

Reduced Myocardial Flow Reserve by Positron Emission Tomography Predicts Cardiovascular Events After Cardiac Transplantation

BACKGROUND

We evaluated the diagnostic and prognostic value of quantification of myocardial flow reserve (MFR) with positron emission tomography (PET) in orthotopic heart transplant patients.

METHODS AND RESULTS

We retrospectively identified orthotopic heart transplant patients who underwent rubidium-82 cardiac PET imaging. The primary outcome was the composite of cardiovascular death, acute coronary syndrome, coronary revascularization, and heart failure hospitalization. Cox regression was used to evaluate the association of MFR with the primary outcome. The relationship of MFR and cardiac allograft vasculopathy severity in patients with angiography within 1 year of PET imaging was assessed using Spearman rank correlation and logistic regression. A total of 117 patients (median age, 60 years; 71% men) were identified. Twenty-one of 62 patients (34%) who underwent angiography before PET had cardiac allograft vasculopathy. The median time from orthotopic heart transplant to PET imaging was 6.4 years (median global MFR, 2.31). After a median of 1.4 years, 22 patients (19%) experienced the primary outcome. On an unadjusted basis, global MFR (hazard ratio, 0.22 per unit increase; 95% confidence interval, 0.09-0.50; P<0.001) and stress myocardial blood flow (hazard ratio, 0.48 per unit increase; 95% confidence interval, 0.29-0.79; P=0.004) were associated with the primary outcome. Decreased MFR independently predicted the primary outcome after adjustment for other variables. In 42 patients who underwent angiography within 12 months of PET, MFR and stress myocardial blood flow were associated with moderate-severe cardiac allograft vasculopathy (International Society of Heart and Lung Transplantation grade 2-3).

CONCLUSIONS

MFR assessed by cardiac rubidium-82 PET imaging is a predictor of cardiovascular events after orthotopic heart transplant and is associated with cardiac allograft vasculopathy severity.

Myocardial perfusion reserve and global longitudinal strain as potential markers of coronary allograft vasculopathy in late-stage orthotopic heart transplantation

Coronary allograft vasculopathy (CAV) is a major cause of mortality in late-stage orthotopic heart transplantation (OHT) patients. Recent evidence has shown that myocardial perfusion reserve (MPR) derived from vasodilator cardiovascular magnetic resonance imaging (vCMR) and global longitudinal strain (GLS) from transthoracic echocardiography (TTE) are useful to detect CAV. However, previous studies have not comprehensively addressed whether these parameters are confounded by allograft rejection, myocardial scar/fibrosis, or allograft dysfunction. Our aim was to determine whether changes in late post-OHT MPR and GLS are due to CAV or other confounding factors. Twenty OHT patients (time from transplant to vCMR was 8.1 ± 4.1 years) and 30 controls (10 healthy volunteers and 20 with prior myocardial infarction to provide perspective with regards to the severity of any abnormalities seen in post-OHT patients) underwent vasodilator vCMR from which MPR index (MPRi), left ventricular ejection fraction (LVEF), and burden of late gadolinium enhancement (LGE) were quantified. TTE was used to measure GLS. The presence of CAV was determined from invasive coronary angiograms using thrombolysis in myocardial infarction (TIMI) frame counts and grading severity per guidelines. Previous endomyocardial biopsies were reviewed to assess association with episodes of rejection. We examined the correlations between MPRi and GLS with markers of CAV, allograft function, scar/fibrosis, and rejection. MPRi was abnormal in post-OHT patients compared to both healthy volunteers and MI controls. While there was no relationship between MPRi or GLS and LVEF, episodes of rejection, or LGE burden, both MPRi and GLS were associated with TIMI frame counts and presence and severity of CAV. Additionally, MPRi correlated with GLS (R = 0.68, P = 0.0002). In conclusion, MPRi and GLS are abnormal in late-stage OHT and associated with CAV, but not related to allograft rejection, myocardial scar/fibrosis, or allograft dysfunction. Non-invasive monitoring of MPRi and GLS may be a useful strategy to detect CAV.