Improved regional myocardial blood flow and flow reserve after coronary revascularization as assessed by serial 15O-water positron emission tomography/computed tomography

Association between optical coherence tomography-defined culprit morphologies and changes in hyperemic coronary flow after elective stenting assessed by transthoracic Doppler echocardiography

BACKGROUND

Stress-transthoracic Doppler echocardiography (S-TDE) provides a noninvasive assessment of coronary flow parameters in the left anterior descending artery (LAD). However, the association between morphological characteristics and coronary flow changes after elective percutaneous coronary intervention (PCI) remains unclear. We aimed to evaluate the relationships between periprocedural coronary flow changes observed on S-TDE and lesion-specific plaque characteristics obtained by optical coherence tomography (OCT) in the interrogated vessels in patients with chronic coronary syndrome (CCS).

METHODS AND RESULTS

Patients with CCS who underwent pre- and post-PCI S-TDE and elective fractional flow reserve (FFR)-guided PCI under OCT guidance for de novo single LAD lesions were included. S-TDE-derived hyperemic diastolic peak flow velocity (hDPV) was used as a surrogate for coronary flow. Lesions were categorized into two groups based on the %hDPV increase or decrease. The baseline clinical, physiological, and OCT findings were compared between the groups. In total, 103 LAD lesions were studied in 103 patients. After PCI, hDPV significantly increased from 55.6 cm/s to 69.5 cm/s (P<0.01), with a median %hDPV increase of 27.2 (6.32-59.1) %, while %hDPV decreased in 20 (19.4%) patients. The FFR improved in all patients. On OCT, layered plaques were more frequently present in the culprit vessels in the %hDPV-decrease group than in the %hDPV-increase group (85.0% vs. 50.6%, P = 0.01). Multivariable logistic regression analysis showed that the presence of layered plaques and high pre-PCI hDPV were independent predictors of %hDPV decrease.

CONCLUSIONS

In patients who underwent successful uncomplicated elective PCI for de novo single LAD lesions, the presence of layered plaques was independently associated with hyperemic coronary flow decrease as assessed by S-TDE.

Myocardial perfusion imaging by 15O-H2O positron emission tomography predicts clinical revascularization procedures in symptomatic patients with previous coronary artery bypass graft

Aims

We wanted to assess if ¹⁵O-H₂O myocardial perfusion imaging (MPI) in a clinical setting can predict referral to coronary artery catheterization [coronary angiography (CAG)], execution of percutaneous coronary intervention (PCI), and post-PCI angina relief for patients with angina and previous coronary artery bypass graft (CABG).

Methods and results

We analysed 172 symptomatic CABG patients referred for ¹⁵O-H₂O positron emission tomography (PET) MPI at Aarhus University Hospital Department of Nuclear Medicine & PET Centre, of which five did not complete the scan. In total, 145 (87%) enrolled patients had an abnormal MPI. Of these, 86/145 (59%) underwent CAG within 3 months; however, no PET parameters predicted referral to CAG. During the CAG, 25/86 (29%) patients were revascularized by PCI. Relative flow reserve (RFR) (0.49 vs. 0.54 P = 0.03), vessel-specific myocardial blood flow (MBF) (1.53 vs. 1.88 mL/g/min, P < 0.01), and vessel-specific myocardial flow reserve (MFR) (1.73 vs. 2.13, P < 0.01) were significantly lower in patients revascularized by PCI. Receiver operating characteristic analysis of the vessel-specific parameters yielded optimal cutoffs of 1.36 mL/g/min (MBF) and 1.28 (MFR) to predict PCI. Angina relief was experienced by 18/24 (75%) of the patients who underwent PCI. Myocardial blood flow was an excellent predictor of angina relief on both a global [area under the curve (AUC) = 0.85, P < 0.01] and vessel-specific (AUC = 0.90, P < 0.01) level with optimal cutoff levels of 1.99 mL/g/min and 1.85 mL/g/min, respectively.

Conclusion

For CABG patients, RFR, vessel-specific MBF, and vessel-specific MFR measured by ¹⁵O-H₂O PET MPI predict whether subsequent CAG will result in PCI. Additionally, global and vessel-specific MBF values predict post-PCI angina relief.

Enhanced myocardial blood flow in ischemic cardiomyopathy by a slow-release synthetic prostacyclin agonist combined with coronary artery bypass grafting: The first human study in a Phase I/IIa clinical trial

Background

YS-1402, which is a polymerized form of the synthetic prostacyclin agonist ONO-1301, has been proven in several preclinical studies to induce therapeutic effects for patients with ischemic cardiomyopathy (ICM). In this human study, we assessed the safety, tolerability, and efficacy of YS-1402, combined with coronary artery bypass grafting (CABG), for ICM.

Methods

Twenty-four patients with ICM whose left ventricular ejection fraction was <40% with an indication for CABG were double-blindly assigned to four groups: placebo, 10-mg YS-1402, 30-mg YS-1402, and 100-mg YS-1402. YS-1402 or placebo medications were administered on the surface of the left ventricle at the time of the CABG. Pre- and postoperative cardiac function and myocardial blood flow were assessed for 6 months postoperatively, along with a safety assessment.

Results

No severe adverse events were related to YS-1402. The maximum blood concentration of ONO-1301 was less than that of the no observable adverse effect level. Significantly increased myocardial blood flow (MBF) and cardiac function were observed in the YS-1402 group 26 weeks postoperatively, although no improvement in MBF occurred in the placebo group.

Conclusion

This Phase I/IIa parallel group-controlled, dose-escalation study of YS-1402 combined with CABG for ICM demonstrated the safety, tolerability, and potential efficacy of YS-1402.

The Role of Angiogenesis and Arteriogenesisin Myocardial Infarction and Coronary Revascularization

Surgical myocardial revascularization is associated with long-term survival benefit in patients with multivessel coronary artery disease. However, the exact biological mechanisms underlying the clinical benefits of myocardial revascularization have not been elucidated yet. Angiogenesis and arteriogenesis biologically leading to vascular collateralization are considered one of the endogenous mechanisms to preserve myocardial viability during ischemia, and the presence of coronary collateralization has been regarded as one of the predictors of long-term survival in patients with coronary artery disease (CAD). Some experimental studies and indirect clinical evidence on chronic CAD confirmed an angiogenetic response induced by myocardial revascularization and suggested that revascularization procedures could constitute an angiogenetic trigger per se. In this review, the clinical and basic science evidence regarding arteriogenesis and angiogenesis in both CAD and coronary revascularization is analyzed with the aim to better elucidate their significance in the clinical arena and potential therapeutic use.

Quantitative Myocardial Perfusion Predicts Outcomes in Patients With Prior Surgical Revascularization

BACKGROUND

Patients with previous coronary artery bypass graft (CABG) surgery typically have complex coronary disease and remain at high risk of adverse events. Quantitative myocardial perfusion indices predict outcomes in native vessel disease, but their prognostic performance in patients with prior CABG is unknown.

OBJECTIVES

In this study, we sought to evaluate whether global stress myocardial blood flow (MBF) and perfusion reserve (MPR) derived from perfusion mapping cardiac magnetic resonance (CMR) independently predict adverse outcomes in patients with prior CABG.

METHODS

This was a retrospective analysis of consecutive patients with prior CABG referred for adenosine stress perfusion CMR. Perfusion mapping was performed in-line with automated quantification of MBF. The primary outcome was a composite of all-cause mortality and major adverse cardiovascular events defined as nonfatal myocardial infarction and unplanned revascularization. Associations were evaluated with the use of Cox proportional hazards models after adjusting for comorbidities and CMR parameters.

RESULTS

A total of 341 patients (median age 67 years, 86% male) were included. Over a median follow-up of 638 days (IQR: 367-976 days), 81 patients (24%) reached the primary outcome. Both stress MBF and MPR independently predicted outcomes after adjusting for known prognostic factors (regional ischemia, infarction). The adjusted hazard ratio (HR) for 1 mL/g/min of decrease in stress MBF was 2.56 (95% CI: 1.45-4.35) and for 1 unit of decrease in MPR was 1.61 (95% CI: 1.08-2.38).

CONCLUSIONS

Global stress MBF and MPR derived from perfusion CMR independently predict adverse outcomes in patients with previous CABG. This effect is independent from the presence of regional ischemia on visual assessment and the extent of previous infarction.

Preprocedural transthoracic Doppler echocardiography to identify stenosis associated with increased coronary flow after revascularisation

The benefit of percutaneous coronary intervention (PCI) has been reported to be associated with functional stenosis severity defined by fractional flow reserve (FFR). This study aimed to investigate the predictive ability of preprocedural transthoracic Doppler echocardiography (TDE) for increased coronary flow. A total of 50 left anterior descending arteries (LAD) that underwent TDE examinations were analysed. Hyperaemic LAD diastolic peak velocity (hDPV) was used as a surrogate of volumetric coronary flow. The increase in coronary flow was evaluated by the metric of % hDPV-increase defined by 100× (post-PCI hDPV-pre-PCI hDPV)/pre-PCI hDPV. The two groups divided by the median value of % hDPV-increase were compared, and the determinants of a significant coronary flow increase defined as more than the median % hDPV-increase were explored. After PCI, FFR values improved in all cases. hDPV significantly increased from 53.0 to 76.0 mm/s (P < 0.01) and the median % hDPV-increase was 45%, while hDPV decreased in 10 patients. On multivariable analysis, pre-PCI FFR and hDPV were independent predictors of a significant coronary flow increase. Preprocedural TDE-derived hDPV provided significant improvement of identification of lesions that benefit from revascularisation with respect to significant coronary flow increase.

Non-invasive Ischaemia Testing in Patients With Prior Coronary Artery Bypass Graft Surgery: Technical Challenges, Limitations, and Future Directions

Coronary artery bypass graft (CABG) surgery effectively relieves symptoms and improves outcomes. However, patients undergoing CABG surgery typically have advanced coronary atherosclerotic disease and remain at high risk for symptom recurrence and adverse events. Functional non-invasive testing for ischaemia is commonly used as a gatekeeper for invasive coronary and graft angiography, and for guiding subsequent revascularisation decisions. However, performing and interpreting non-invasive ischaemia testing in patients post CABG is challenging, irrespective of the imaging modality used. Multiple factors including advanced multi-vessel native vessel disease, variability in coronary hemodynamics post-surgery, differences in graft lengths and vasomotor properties, and complex myocardial scar morphology are only some of the pathophysiological mechanisms that complicate ischaemia evaluation in this patient population. Systematic assessment of the impact of these challenges in relation to each imaging modality may help optimize diagnostic test selection by incorporating clinical information and individual patient characteristics. At the same time, recent technological advances in cardiac imaging including improvements in image quality, wider availability of quantitative techniques for measuring myocardial blood flow and the introduction of artificial intelligence-based approaches for image analysis offer the opportunity to re-evaluate the value of ischaemia testing, providing new insights into the pathophysiological processes that determine outcomes in this patient population.

Myocardial T1-mapping and Extracellular Volume Quantification in Patients and Putative Carriers of Muscular Dystrophy: Early Experience

To assess myocardial fibrosis associated with muscular dystrophy, T₁-mapping and extracellular volume fraction (ECV) quantification was prospectively performed using cardiovascular MR (CMR) imaging in 6 male patients with muscular dystrophy and 5 female putative carriers of Duchenne or Becker muscular dystrophy. Five patients and all putative carriers had an elevated ECV (>29.5% for men and >35.2% for women), suggesting that ECV has a potential to detect diffuse fibrotic changes in patients and putative carriers of muscular dystrophy.

Early effect of percutaneous coronary intervention of non-left anterior descending artery on coronary flow velocity reserve of left anterior descending artery assessed by transthoracic Doppler echocardiography

Background

Limited data are available regarding the influence of percutaneous coronary intervention (PCI) of non-totally occluded lesions (non-CTO) on the coronary flow of non-target vessels. We sought to investigate the short-term impact of the non-left anterior descending artery (non-LAD) PCI on the coronary flow physiology of LAD using transthoracic Doppler echocardiography (TDE).

Methods and results

We consecutively studied 50 patients who underwent successful PCI of non-LAD and non-CTO lesions and a coronary flow velocity assessment of LAD at rest and maximal hyperemia before and at 2 days after the procedure by TDE. Coronary flow velocity reserve (CFVR) was calculated as the ratio of hyperemic to resting diastolic peak velocity (hDPV/bDPV). We evaluated the changes in LAD coronary flow characteristics after PCI of non-LAD and explored the determinants of the change in LAD-CFVR. The median fractional flow reserve (FFR) of the culprit lesion and the LAD quantitative flow ratio (QFR) were 0.67 and 0.88, respectively. After non-LAD PCI, LAD-CFVR was decreased in 33 patients (66.0%). LAD-CFVR significantly decreased (pre-PCI: 2.41, post-PCI: 2.03, p = 0.001) due to a significant decrease in LAD-hDPV (P = 0.007). The prevalence of impaired LAD-CFVR (≤2.0) significantly increased (pre: 30%, post: 48%, P = 0.027). Multivariable linear regression analysis showed that pre-PCI LAD-CFVR was independent predictor of the change in LAD-CFVR after PCI.

Conclusions

LAD-CFVR significantly decreased after successful non-LAD PCI due to the postprocedural reduction of coronary flow assessed by LAD-hDPV.