Reduced global myocardial perfusion reserve in DCM and HCM patients assessed by CMR-based velocity-encoded coronary sinus flow measurements and first-pass perfusion imaging

The predictive value of coronary microvascular dysfunction for left ventricular reverse remodelling in dilated cardiomyopathy

Aims

To evaluate the degree of coronary microvascular dysfunction (CMD) in dilated cardiomyopathy (DCM) patients by cardiac magnetic resonance (CMR) first-pass perfusion parameters and to examine the correlation between myocardial perfusion and left ventricle reverse remodelling (LVRR).

Methods

In this study, 94 DCM patients and 35 healthy controls matched for age and sex were included. Myocardial perfusion parameters, including upslope, time to maximum signal intensity (Timemax), maximum signal intensity (SImax), baseline signal intensity (SIbaseline), and the difference between maximum and baseline signal intensity (SImax-baseline) were measured. Additionally, left ventricular (LV) structure, function parameters, and late gadolinium enhancement (LGE) were also recorded. The parameters were compared between healthy controls and DCM patients. Univariable and multivariable logistic regression analyses were used to determine the predictors of LVRR.

Results

With a median follow-up period of 12 months [interquartile range (IQR), 8-13], 41 DCM patients (44%) achieved LVRR. Compared with healthy controls, DCM patients presented CMD with reduced upslope, SIbaseline, and increased Timemax (all p < 0.01). Timemax, SImax, and SImax-baseline were further decreased in LVRR than non-LVRR group (Timemax: 60.35 [IQR, 51.46-74.71] vs. 72.41 [IQR, 59.68-97.70], p = 0.017; SImax: 723.52 [IQR, 209.76-909.27] vs. 810.92 [IQR, 581.30-996.89], p = 0.049; SImax-baseline: 462.99 [IQR, 152.25-580.43] vs. 551.13 [IQR, 402.57-675.36], p = 0.038). In the analysis of multivariate logistic regression, Timemax [odds ratio (OR) 0.98; 95% confidence interval (CI) 0.95-1.00; p = 0.032)], heart rate (OR 1.04; 95% CI 1.01-1.08; p = 0.029), LV remodelling index (OR 1.73; 95% CI 1.06-3.00; p = 0.038) and LGE extent (OR 0.85; 95% CI 0.73-0.96; p = 0.021) were independent predictors of LVRR.

Conclusions

CMD could be found in DCM patients and was more impaired in patients with non-LVRR than LVRR patients. Timemax at baseline was an independent predictor of LVRR in DCM.

Coronary microvascular dysfunction and myocardial infarction with non-obstructive coronary arteries: Where do we stand?

In the past decade, scientific and clinical research has provided a translational perspective on myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA). MINOCA is characterized by clinical documentation of an acute MI but angiography shows no significant coronary artery obstruction (stenosis <50%). The prevalence of MINOCA is estimated to range from approximately 6 to 10% among MI patients, and those with this condition have a poor prognosis, experiencing high rates of mortality, rehospitalization, and socioeconomic burden. MINOCA represents a major unmet need in cardiovascular medicine, with uncertain clinical management. It is a complex condition that can be caused by various factors, including atherosclerosis, plaque rupture, coronary vasospasm, and microvascular dysfunction. Effective management of MINOCA depends on identifying the underlying mechanism of the infarction, thus a systematic diagnostic approach is recommended. Contemporary data shows that a significant number of patients exhibit structural and functional abnormalities in coronary microcirculation, which is referred to as coronary microvascular dysfunction (CMD). CMD plays a crucial role in patients with signs and symptoms of myocardial ischemia and non-obstructive coronary artery stenosis, including MINOCA. Furthermore, conducting a thorough evaluation of coronary function can have significant prognostic and therapeutic implications, since personalized patient management strategies based on this assessment have been shown to improve symptoms and prognosis. Therefore, an accurate and timely diagnosis of CMD is essential for effective patient management, which can be achieved through various invasive and non-invasive methods. This review will discuss the pathophysiological understanding, current diagnostic techniques, and management strategies of patients with MINOCA and CMD.

Coronary flow reserve evaluated by phase-contrast cine cardiovascular magnetic resonance imaging of coronary sinus: a meta-analysis

BACKGROUND

Phase-contrast cine cardiovascular magnetic resonance (CMR) of the coronary sinus has emerged as a non-invasive method for measuring coronary sinus blood flow and coronary flow reserve (CFR). However, its clinical utility has not yet been established. Here we performed a meta-analysis to clarify the clinical value of CMR-derived CFR in various cardiovascular diseases.

METHODS

An electronic database search was performed of PubMed, Web of Science Core Collection, Cochrane Advanced Search, and EMBASE. We compared the CMR-derived CFR of various cardiovascular diseases (stable coronary artery disease [CAD], hypertrophic cardiomyopathy [HCM], dilated cardiomyopathy [DCM]) and control subjects. We assessed the prognostic value of CMR-derived CFR for predicting major adverse cardiac events (MACE) in patients with stable CAD.

RESULTS

A total of 47 eligible studies were identified. The pooled CFR from our meta-analysis was 3.48 (95% confidence interval [CI], 2.98-3.98) in control subjects, 2.50 (95% CI, 2.38-2.61) in stable CAD, 2.01 (95% CI, 1.70-2.32) in cardiomyopathies (HCM and DCM). The meta-analysis showed that CFR was significantly reduced in stable CAD (mean difference [MD] = -1.48; 95% CI, -1.78 to -1.17; p < 0.001; I2 = 0%; p for heterogeneity = 0.33), HCM (MD = -1.20; 95% CI, -1.63 to -0.77; p < 0.001; I2 = 0%; p for heterogeneity = 0.49), and DCM (MD = -1.53; 95% CI, -1.93 to -1.13; p < 0.001; I2 = 0%; p for heterogeneity = 0.45). CMR-derived CFR was an independent predictor of MACE for patients with stable CAD (hazard ratio = 0.52 per unit increase; 95% CI, 0.37-0.73; p < 0.001; I2 = 84%, p for heterogeneity < 0.001).

CONCLUSIONS

CMR-derived CFR was significantly decreased in cardiovascular diseases, and a decreased CFR was associated with a higher occurrence of MACE in patients with stable CAD. These results suggest that CMR-derived CFR has potential for the pathological evaluation of stable CAD, cardiomyopathy, and risk stratification in CAD.

A cardiovascular magnetic resonance imaging-based pilot study to assess coronary microvascular disease in COVID-19 patients

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and is primarily characterised by a respiratory disease. However, SARS-CoV-2 can directly infect vascular endothelium and subsequently cause vascular inflammation, atherosclerotic plaque instability and thereby result in both endothelial dysfunction and myocardial inflammation/infarction. Interestingly, up to 50% of patients suffer from persistent exercise dyspnoea and a post-viral fatigue syndrome (PVFS) after having overcome an acute COVID-19 infection. In the present study, we assessed the presence of coronary microvascular disease (CMD) by cardiovascular magnetic resonance (CMR) in post-COVID-19 patients still suffering from exercise dyspnoea and PVFS. N = 22 patients who recently recovered from COVID-19, N = 16 patients with classic hypertrophic cardiomyopathy (HCM) and N = 17 healthy control patients without relevant cardiac disease underwent dedicated vasodilator-stress CMR studies on a 1.5-T MR scanner. The CMR protocol comprised cine and late-gadolinium-enhancement (LGE) imaging as well as velocity-encoded (VENC) phase-contrast imaging of the coronary sinus flow (CSF) at rest and during pharmacological stress (maximal vasodilation induced by 400 µg IV regadenoson). Using CSF measurements at rest and during stress, global myocardial perfusion reserve (MPR) was calculated. There was no difference in left ventricular ejection-fraction (LV-EF) between COVID-19 patients and controls (60% [57–63%] vs. 63% [60–66%], p = NS). There were only N = 4 COVID-19 patients (18%) showing a non-ischemic pattern of LGE. VENC-based flow measurements showed that CSF at rest was higher in COVID-19 patients compared to controls (1.78 ml/min [1.19–2.23 ml/min] vs. 1.14 ml/min [0.91–1.32 ml/min], p = 0.048). In contrast, CSF during stress was lower in COVID-19 patients compared to controls (3.33 ml/min [2.76–4.20 ml/min] vs. 5.32 ml/min [3.66–5.52 ml/min], p = 0.05). A significantly reduced MPR was calculated in COVID-19 patients compared to healthy controls (2.73 [2.10–4.15–11] vs. 4.82 [3.70–6.68], p = 0.005). No significant differences regarding MPR were detected between COVID-19 patients and HCM patients. In post-COVID-19 patients with persistent exertional dyspnoea and PVFS, a significantly reduced MPR suggestive of CMD—similar to HCM patients—was observed in the present study. A reduction in MPR can be caused by preceding SARS-CoV-2-associated direct as well as secondary triggered mechanisms leading to diffuse CMD, and may explain ongoing symptoms of exercise dyspnoea and PVFS in some patients after COVID-19 infection.

Prediction of Serious Adverse Events of Patients with Hypertrophic Cardiomyopathy by Magnetic Resonance

Although it is well known that patients with hypertrophic cardiomyopathy (HCM) have serious adverse events, such as life-threatening arrhythmia and heart failure, the prediction of such evens is still difficult. Recently, it has been reported that one of the causes of these serious adverse events is microvascular dysfunction, which can be noninvasively evaluated by employing cardiac magnetic resonance (CMR) imaging.We analyzed 32 consecutive HCM patients via CMR imaging and myocardial scintigraphy and divided them into two groups: ventricular tachycardia (VT) group and non-VT group. Myocardial perfusion studies were conducted quantitatively using the QMass^® software, and each slice image was divided into six segments. The time-intensity curve derived from the perfusion image by CMR imaging was evaluated, and the time to 50% of the peak intensity (time 50% max) was automatically calculated for each segment.Although no difference was observed in various parameters of myocardial scintigraphy between the two groups, the VT group exhibited a higher mean of time 50% max and wider standard deviation (SD) of time 50% max in each segment than the non-VT group. The cutoff values were obtained by the receiver operating characteristic curves derived from the mean of time 50% max and SD of time 50% max. The two groups divided by the cutoff values exhibited significant differences in the occurrence of serious adverse events.CMR imaging may be useful for predicting serious adverse events of patients with HCM.

Clinical and electrocardiographic features of patients with myocardial infarction with non-obstructive coronary artery disease (MINOCA)

AIMS

Myocardial infarction with non-obstructive coronary artery disease (MINOCA) is often an underdiagnosed and undertreated condition. This study aimed to evaluate clinical and ECG characteristics of MINOCA in a large cohort of patients admitted for acute coronary syndrome.

METHODS

All coronary angiograms performed at the University Heart Center in Zurich (Switzerland) between 2012 and 2016 were investigated. MINOCA was defined according to European Society of Cardiology guidelines and patients were divided into two groups, based on the presence or absence of coronary sclerosis at angiogram[nonobstructive coronary artery disease (noCAD) and normal coronary arteries (NCA)]), after exclusion of myocarditis and Takotsubo syndrome.

RESULTS

Out of 13 669 angiographic studies, 3695 were diagnosed with acute coronary syndrome; of these, 244 patients presented MINOCA (6.6%). Patients with noCAD were more likely to be older (67.9 vs. 59.2 years, P < 0.001) with higher prevalence of traditional cardiovascular risk factors (hypertension 64.1 vs. 41.2%, P = 0.002; diabetes 19.7 vs. 10.8%, P = 0.036; hypercholesterolemia 36.6 vs. 23.5%, P = 0.037). On surface ECG, anterior ST- segment elevation was more frequent in NCA patients (13.7 vs. 5.0%, P = 0.016). Secondary prevention therapy was significantly more prescribed in noCAD compared with NCA patients (acetylsalicylic acid 68.3 vs. 21.6%, P less than 0.001; statins 76.1 vs. 22.5%, P less than 0.001; angiotensin-converting enzyme inhibitor-AT1 blockers 51.4 vs. 31.3%, P = 0.006). One-year mortality was very low (0.4% for noCAD patients).

CONCLUSION

noCAD patients were older, with higher prevalence of cardiovascular risk factors and more frequently discharged with secondary prevention therapy. NCA patients presented more frequently anterior ST- segment elevation. Further diagnostic tests should be highly recommended to determine the underlying mechanism of MINOCA.

Age- and gender-related reference values of cardiac morphology and function in cardiovascular magnetic resonance

Cardiovascular magnetic resonance (CMR) is the reference standard for the quantitative assessment of cardiac morphology and function. The aim of the study was to determine age- and gender-related reference values for cardiac morphology and function according to current recommendations. 454 healthy volunteers (235 men, median age 52.0 (44.0-59.0) years) underwent a standard CMR scan and were divided into six groups of nearly equal size with regard to sex (male, female) and age (21-47 years, 48-57 years, 58-84 years). Left ventricular end-diastolic (LV-EDV) and end-systolic (LV-ESV) volumes and LV mass (LV-M) were measured at end-diastole and end-systole in steady-state free precession series with including papillary muscles and trabecular tissue in the LV-M. Absolute and indexed volumetric parameters were significantly different between gender groups with higher values in men compared to women (all p < 0.001). Furthermore, a significant age-dependent decline could be observed for left ventricular and right ventricular volumes (all p < 0.001), while LV-M did not show differences between the different age-groups. Parameters of longitudinal function for the left and right ventricle were higher in female compared to male subjects with a significant age-dependent decline. We provided normal values for cardiac volumes, function, and mass derived in accordance with current guidelines from a large population of healthy subjects, which can be implemented in clinical routine as a standard of reference.

Diagnostic value of the novel CMR parameter "myocardial transit-time" (MyoTT) for the assessment of microvascular changes in cardiac amyloidosis and hypertrophic cardiomyopathy

BACKGROUND

Coronary microvascular dysfunction (CMD) is present in various non-ischemic cardiomyopathies and in particular in those with left-ventricular hypertrophy. This study evaluated the diagnostic value of the novel cardiovascular magnetic resonance (CMR) parameter "myocardial transit-time" (MyoTT) in distinguishing cardiac amyloidosis from other hypertrophic cardiomyopathies.

METHODS

N = 20 patients with biopsy-proven cardiac amyloidosis (CA), N = 20 patients with known hypertrophic cardiomyopathy (HCM), and N = 20 control patients without relevant cardiac disease underwent dedicated CMR studies on a 1.5-T MR scanner. The CMR protocol comprised cine and late-gadolinium-enhancement (LGE) imaging as well as first-pass perfusion acquisitions at rest for MyoTT measurement. MyoTT was defined as the blood circulation time from the orifice of the coronary arteries to the pooling in the coronary sinus (CS) reflecting the transit-time of gadolinium in the myocardial microvasculature.

RESULTS

MyoTT was significantly prolonged in patients with CA compared to both groups: 14.8 ± 4.1 s in CA vs. 12.2 ± 2.5 s in HCM (p = 0.043) vs. 7.2 ± 2.6 s in controls (p < 0.001). Native T1 and extracellular volume (ECV) were significantly higher in CA compared to HCM and controls (p < 0.001). Both parameters were associated with a higher diagnostic accuracy in predicting the presence of CA compared to MyoTT: area under the curve (AUC) for native T1 = 0.93 (95% confidence interval (CI) = 0.83-1.00; p < 0.001) and AUC for ECV = 0.95 (95% CI = 0.88-1.00; p < 0.001)-compared to the AUC for MyoTT = 0.76 (95% CI = 0.60-0.92; p = 0.008). In contrast, MyoTT performed better than all other CMR parameters in differentiating HCM from controls (AUC for MyoTT = 0.93; 95% CI = 0.81-1.00; p = 0.003 vs. AUC for native T1 = 0.69; 95% CI = 0.44-0.93; p = 0.20 vs. AUC for ECV = 0.85; 95% CI = 0.66-1.00; p = 0.017).

CONCLUSION

The relative severity of CMD (measured by MyoTT) in relationship to extracellular changes (measured by native T1 and/or ECV) is more pronounced in HCM compared to CA-in spite of a higher absolute MyoTT value in CA patients. Hence, MyoTT may improve our understanding of the interplay between extracellular/intracellular and intravasal changes that occur in the myocardium during the disease course of different cardiomyopathies.

Diagnosis of coronary microvascular dysfunction in the clinic

The coronary microcirculation plays a pivotal role in the regulation of coronary blood flow and cardiac metabolism. It can adapt to acute and chronic pathologic conditions such as coronary thrombosis or long-standing hypertension. Due to the fact that the coronary microcirculation cannot be visualized in human beings in vivo, its assessment remains challenging. Thus, the clinical importance of the coronary microcirculation is still often underestimated or even neglected. Depending on the clinical condition of the respective patient, several non-invasive (e.g. transthoracic Doppler-echocardiography assessing coronary flow velocity reserve, cardiac magnetic resonance imaging, positron emission tomography) and invasive methods (e.g. assessment of coronary flow reserve (CFR) and microvascular resistance (MVR) using adenosine, microvascular coronary spasm with acetylcholine) have been established for the assessment of coronary microvascular function. Individual patient characteristics, but certainly also local availability, methodical expertise and costs will influence which methods are being used for the diagnostic work-up (non-invasive and/or invasive assessment) in a patient with recurrent symptoms and suspected coronary microvascular dysfunction. Recently, the combined invasive assessment of coronary vasoconstrictor as well as vasodilator abnormalities has been titled interventional diagnostic procedure (IDP). It involves intracoronary acetylcholine testing for the detection of coronary spasm as well as CFR and MVR assessment in response to adenosine using a dedicated wire. Currently, the IDP represents the most comprehensive coronary vasomotor assessment. Studies using the IDP to better characterize the endotypes observed will hopefully facilitate development of tailored and effective treatments.

Nucleotide ecto-enzyme metabolic pattern and spatial distribution in calcific aortic valve disease; its relation to pathological changes and clinical presentation

BACKGROUND

Extracellular nucleotide metabolism contributes to chronic inflammation, cell differentiation, and tissue mineralization by controlling nucleotide and adenosine concentrations and hence its purinergic effects. This study investigated location-specific changes of extracellular nucleotide metabolism in aortic valves of patients with calcific aortic valve disease (CAVD). Individual ecto-enzymes and adenosine receptors involved were analyzed together with correlation with CAVD severity and risk factors.

RESULTS

Nucleotide and adenosine degradation rates were adversely modified on the aortic surface of stenotic valve as compared to ventricular side, including decreased ATP removal (1.25 ± 0.35 vs. 2.24 ± 0.61 nmol/min/cm2) and adenosine production (1.32 ± 0.12 vs. 2.49 ± 0.28 nmol/min/cm2) as well as increased adenosine deamination (1.28 ± 0.31 vs. 0.67 ± 0.11 nmol/min/cm2). The rates of nucleotide to adenosine conversions were lower, while adenosine deamination was higher on the aortic sides of stenotic vs. non-stenotic valve. There were no differences in extracellular nucleotide metabolism between aortic and ventricular sides of non-stenotic valves. Furthermore, nucleotide degradation rates, measured on aortic side in CAVD (n = 62), negatively correlated with echocardiographic and biochemical parameters of disease severity (aortic jet velocity vs. ATP hydrolysis: r = - 0.30, p < 0.05; vs. AMP hydrolysis: r = - 0.44, p < 0.001; valvular phosphate concentration vs. ATP hydrolysis: r = - 0.26, p < 0.05; vs. AMP hydrolysis: r = - 0.25, p = 0.05) while adenosine deamination showed positive correlation trend with valvular phosphate deposits (r = 0.23, p = 0.07). Nucleotide and adenosine conversion rates also correlated with CAVD risk factors, including hyperlipidemia (AMP hydrolysis vs. serum LDL cholesterol: r = - 0.28, p = 0.05; adenosine deamination vs. total cholesterol: r = 0.25, p = 0.05; LDL cholesterol: r = 0.28, p < 0.05; triglycerides: r = 0.32, p < 0.05), hypertension (adenosine deamination vs. systolic blood pressure: r = 0.28, p < 0.05) and thrombosis (ATP hydrolysis vs. prothrombin time: r = - 0.35, p < 0.01). Functional assays as well as histological and immunofluorescence, flow cytometry and RT-PCR studies identified all major ecto-enzymes engaged in nucleotide metabolism in aortic valves that included ecto-nucleotidases, alkaline phosphatase, and ecto-adenosine deaminase. We have shown that changes in nucleotide-converting ecto-enzymes were derived from their altered activities on valve cells and immune cell infiltrate. We have also demonstrated a presence of A1, A2a and A2b adenosine receptors with diminished expression of A2a and A2b in stenotic vs. non-stenotic valves. Finally, we revealed that augmenting adenosine effects by blocking adenosine deamination with deoxycoformycin decreased aortic valve thickness and reduced markers of calcification via adenosine-dependent pathways in a mouse model of CAVD.

CONCLUSIONS

This work highlights profound changes in extracellular nucleotide and adenosine metabolism in CAVD. Altered extracellular nucleotide hydrolysis and degradation of adenosine in stenotic valves may affect purinergic responses to support a pro-stenotic milieu and valve calcification. This emphasizes a potential mechanism and target for prevention and therapy. .

"Myocardial transit-time" (MyoTT): a novel and easy-to-perform CMR parameter to assess microvascular disease

BACKGROUND

Myocardial microvascular disease may occur during the disease course of different cardiac as well as systemic disorders. With the present study, we introduce a novel and easy-to-perform cardiovascular magnetic resonance (CMR) parameter named "myocardial transit-time" (MyoTT).

METHODS

N = 20 patients with known hypertrophic cardiomyopathy (HCM) and N = 20 control patients without relevant cardiac disease underwent dedicated CMR studies on a 1.5-T MR scanner. The CMR protocol comprised cine and late-gadolinium-enhancement (LGE) imaging as well as first-pass perfusion acquisitions at rest for MyoTT measurement. MyoTT was defined as the blood circulation time from the orifice of the coronary arteries to the pooling in the coronary sinus (CS), and accordingly measured as the temporal difference between the appearances of CMR contrast agent in the aortic root and the CS reflecting the transit-time of gadolinium in the myocardial microvasculature.

RESULTS

Patients with HCM had a significantly prolonged MyoTT compared to controls (11.0 (9.1-14.5) s vs. 6.5 (4.8-8.4) s, p < 0.001). This significant difference did not change when the individual heart rate was taken into consideration (MyoTT indexed, p < 0.001). Significant correlations were found between MyoTT and maximal left ventricular (LV) wall thickness (r = 0.771, p < 0.001), MyoTT and presence of LGE (r = 0.760, p < 0.001) as well as MyoTT and LV global longitudinal strain (r = 0.672, p < 0.001). ROC analysis resulted in an area-under-curve (AUC) of 0.90 for MyoTT and showed an optimal sensitivity/specificity cut-off of 7.85 s to differentiate HCM from controls.

CONCLUSION

"Myocardial transit-time" is a novel and easy-to-perform CMR parameter that allows a quick assessment of the extent of myocardial microvascular disease. This novel CMR parameter may open new vistas in the assessment of microvascular disease-not only in HCM patients. Future studies will show the usefulness and clinical relevance of this novel CMR parameter.