Thermodilutional Confirmation of Coronary Microvascular Dysfunction in Patients With Recurrent Angina After Successful Percutaneous Coronary Intervention

Prognostic Value of Microvascular Resistance Reserve Measured Immediately After PCI in Stable Coronary Artery Disease

BACKGROUND

Microvascular resistance reserve (MRR) has been proposed as a specific metric to quantify coronary microvascular function. The long-term prognostic value of MRR measured in stable patients immediately after percutaneous coronary intervention (PCI) is unknown. This study sought to determine the prognostic value of MRR measured immediately after PCI in patients with stable coronary artery disease.

METHODS

This study included 502 patients with stable coronary artery disease who underwent elective PCI and coronary physiological measurements, including pressure and flow estimation using a bolus thermodilution method after PCI. MRR was calculated as coronary flow reserve divided by fractional flow reserve times the ratio of mean aortic pressure at rest to that at maximal hyperemia induced by hyperemic agents. An abnormal MRR was defined as ≤2.5. Major adverse cardiac events (MACEs) were defined as a composite of all-cause mortality, any myocardial infarction, and target-vessel revascularization.

RESULTS

During a median follow-up of 3.4 years, the cumulative MACE rate was significantly higher in the abnormal MRR group (12.5 versus 8.3 per 100 patient-years; hazard ratio 1.53 [95% CI, 1.10-2.11]; P<0.001). A higher all-cause mortality rate primarily drove this difference. On multivariable analysis, a higher MRR value was independently associated with lower MACE and lower mortality. When comparing 4 subgroups according to MRR and the index of microcirculatory resistance, patients with both abnormal MRR and index of microcirculatory resistance (≥25) had the highest MACE rate.

CONCLUSIONS

An abnormal MRR measured immediately after PCI in patients with stable coronary artery disease is an independent predictor of MACE, particularly all-cause mortality.

Coronary microvascular dysfunction: A review of recent progress and clinical implications

The coronary microcirculation plays a cardinal role in regulating coronary blood flow to meet the changing metabolic demands of the myocardium. Coronary microvascular dysfunction (CMD) refers to structural and functional remodeling of the coronary microcirculation. CMD plays a role in the pathogenesis of obstructive and non-obstructive coronary syndromes as well as myocardial diseases, including heart failure with preserved ejection fraction (HFpEF). Despite recent diagnostic advancements, CMD is often under-appreciated in clinical practice, and may allow for the development of novel therapeutic targets. This review explores the diagnosis and pathogenic role of CMD across a range of cardiovascular diseases, its prognostic significance, and the current therapeutic landscape.

Optimal Medical Therapy as First-Line Therapy for Chronic Coronary Syndromes: Lessons from COURAGE, BARI 2D, FAME 2, and ISCHEMIA

The chronic coronary syndromes (CCS) include patients with a classic history of angina pectoris in the presence of either risk factors for or known atherosclerotic coronary artery disease. Randomized, controlled trials conducted in the optimal medical therapy (OMT) era have convincingly demonstrated that adherence to the outdated paradigm focused on treatment of obstructive coronary disease with initial revascularization fails to reduce death or myocardial infarction and inconsistently reduces angina symptoms. Rather, OMT reduces events and improves symptoms and should be considered first-line treatment for patients with CCS.

Predictors of recurrent angina in patients with no need for secondary revascularization

BACKGROUND

Approximately 20% to 30% of patients with coronary artery disease (CAD) develop recurrent angina pectoris following successful and complete coronary revascularization utilizing percutaneous coronary intervention (PCI). We aim to investigate predictors of recurrent angina pectoris in patients who have undergone successful coronary revascularization using PCI, but on repeat coronary angiography have no need for secondary revascularization.

METHODS

The study comprised 3,837 patients with CAD, who were enrolled from January 2007 to June 2019. They had undergone successful PCI; some of them redeveloped angina pectoris within one year after the procedure, but on repeat coronary angiography had no need for revascularization. Thrombolysis in myocardial infarction (TIMI) frame count was used to evaluate the velocity of coronary blood in the follow-up angiogram. Multivariate logistic regression was used to investigate risk factors for recurrent angina pectoris. Similarly, predictors of recurrent angina according to the TIMI frame count were assessed using multivariate linear regression.

RESULTS

In this retrospective study, 53.5% of patients experienced recurrent angina pectoris. By multivariate logistic regression, the following characteristics were statistically identified as risk factors for recurrent angina pectoris: female sex, older age, current smoking, low-density lipoprotein cholesterol (LDL-C) ≥1.8 mmol/L, and an elevated TIMI frame count (P for all <0.05). Similarly, using multivariate linear regression, the statistical risk factors for TIMI frame count included: female sex, older age, diabetes, body mass index (BMI), post-procedural treatment without the inclusion of dual antiplatelet therapy.

CONCLUSIONS

Patient characteristics of female sex, older age, diabetes, and elevated BMI are associated with an increased TIMI frame count, coronary microcirculation dysfunction, and recurrent angina pectoris after initially successful PCI. In addition, current smoking and LDL-C ≥1.8 mmol/L are risk factors for recurrent angina pectoris. In contrast, the treatment with dual antiplatelet therapy is negatively correlated with a higher TIMI frame count and the risk of recurrent angina pectoris.

ACPTI study: Being positive in a negative situation is not naivety - Trimetazidine still has role in symptomatic CAD patients

RESULTS

of the efficAcy and safety of Trimetazidine in patients with angina pectoris having been treated by Percutaneous Coronary Intervention (ATPCI) study showed no significant difference in the incidence of primary endpoint events between trimetazidine and placebo group in angina patients who recently underwent percutaneous coronary intervention. However, the study had limitations specific to both, design and selection of patient population. Here, we present some explanations for the null effects of trimetazidine in the ATPCI study and their relevance in routine clinical practice.

Coronary microvascular dysfunction in stable ischaemic heart disease (non-obstructive coronary artery disease and obstructive coronary artery disease)

Diffuse and focal epicardial coronary disease and coronary microvascular abnormalities may exist side-by-side. Identifying the contributions of each of these three players in the coronary circulation is a difficult task. Yet identifying coronary microvascular dysfunction (CMD) as an additional player in patients with coronary artery disease (CAD) may provide explanations of why symptoms may persist frequently following and why global coronary flow reserve may be more prognostically important than fractional flow reserve measured in a single vessel before percutaneous coronary intervention. This review focuses on the challenges of identifying the presence of CMD in the context of diffuse non-obstructive CAD and obstructive CAD. Furthermore, it is going to discuss the pathophysiology in this complex situation, examine the clinical context in which the interaction of the three components of disease takes place and finally look at non-invasive diagnostic methods relevant for addressing this question.

Mechanisms and diagnostic evaluation of persistent or recurrent angina following percutaneous coronary revascularization

Persistence or recurrence of angina after a percutaneous coronary intervention (PCI) may affect about 20-40% of patients during short-medium-term follow-up. This appears to be true even when PCI is 'optimized' using physiology-guided approaches and drug-eluting stents. Importantly, persistent or recurrent angina post-PCI is associated with a significant economic burden. Healthcare costs may be almost two-fold higher among patients with persistent or recurrent angina post-PCI vs. those who become symptom-free. However, practice guideline recommendations regarding the management of patients with angina post-PCI are unclear. Gaps in evidence into the mechanisms of post-PCI angina are relevant, and more research seems warranted. The purpose of this document is to review potential mechanisms for the persistence or recurrence of angina post-PCI, propose a practical diagnostic algorithm, and summarize current knowledge gaps.

Transmural variation in microvascular remodeling following percutaneous revascularization of a chronic coronary stenosis in swine

Remodeling of the coronary microcirculation is known to occur distal to a chronic coronary stenosis, but the reversibility of these changes and their functional significance on maximum myocardial perfusion before and after revascularization is unknown. Accordingly, swine instrumented with a chronic silastic stenosis on the left anterior descending coronary artery to produce hibernating myocardium underwent percutaneous coronary intervention (PCI; n = 8) and were compared with animals with a persistent stenosis (n = 8), as well as sham controls (n = 6). Stenotic animals demonstrated an increased subendocardial arteriolar wall thickness-to-lumen ratio (37.8 ± 3.3 vs. 28.3 ± 1.3% in sham, P = 0.04), reduced lumen area per arteriole (597 ± 88 vs. 927 ± 113 μm2, P = 0.04), and a compensatory increase in arteriolar density (9.4 ± 1.0 vs. 5.3 ± 0.4 arterioles/mm2, P < 0.01). As a result, vasodilated flow immediately after PCI was similar to normally perfused remote regions (5.1 ± 1.0 vs. 4.8 ± 0.9 ml·min-1·g-1, P = 0.87). When assessed 1-mo after PCI, increases in wall thickness-to-lumen diameter (42.2 ± 3.3%) and reductions in lumen area per arteriole (638 ± 59 μm2) remained unchanged, but arteriolar density returned to normal (5.2 ± 0.5 arterioles/mm2). As a result, maximum subendocardial flow during adenosine declined and was lower than remote regions (2.6 ± 0.3 vs. 5.9 ± 1.1 ml·min-1·g-1, P = 0.01). There was no microvascular remodeling in subepicardial arterioles, and maximum perfusion remained unchanged. These data demonstrate that subendocardial microvascular remodeling occurs distal to a chronic epicardial stenosis. The regression of arteriolar density without increases in luminal area may precipitate stress-induced subendocardial ischemia in the absence of a physiologically significant stenosis.NEW & NOTEWORTHY Swine with a chronic coronary stenosis exhibit subendocardial microvascular remodeling distal to a critical stenosis characterized by an increase in arteriolar wall thickness and reduction in lumen area with a compensatory increase in arteriolar density. The present study is the first to demonstrate that subendocardial arteriolar density normalizes 1-mo after revascularization, but the lumen area of individual arterioles remains reduced. This leads to a reduction in maximal subendocardial perfusion at this time point despite initial normalization of vasodilator reserve after revascularization. This pattern of chronic microvascular structural remodeling could contribute to recurrent subendocardial ischemia in the absence of coronary restenosis during tachycardia and increases in myocardial oxygen demand.

Reappraisal of Ischemic Heart Disease

In recent years, it has become apparent that coronary microvascular dysfunction plays a pivotal pathogenic role in angina pectoris. Functional and structural mechanisms can affect the physiological function of the coronary microvasculature and lead to myocardial ischemia in people without coronary atheromatous disease and also in individuals with obstructive coronary artery disease. Abnormal dilatory responses of the coronary microvessels, coronary microvascular spasm, and extravascular compressive forces have been identified as pathogenic mechanisms in both chronic and acute forms of ischemic heart disease. The condition characterized by anginal symptoms and evidence of myocardial ischemia triggered by coronary microvascular dysfunction, in the absence of obstructive coronary disease, is known as microvascular angina. The concept of microvascular angina, however, may extend further to include patients with obstructive coronary artery disease and individuals with angina after coronary revascularization or heart transplantation because coronary microvascular dysfunction contributes to myocardial ischemia in many such patients. Patients with microvascular angina constitute a sizeable proportion of all cases of stable angina undergoing diagnostic coronary angiography and of those with persisting angina after successful coronary revascularization. Coronary microvascular dysfunction is also often responsible for angina in individuals with cardiomyopathy and heart valve disease as well as acute coronary syndrome cases such as Takotsubo syndrome and myocardial infarction with no obstructive coronary artery disease. Patients with stable microvascular angina present typically with effort or rest chest pain and a reduced coronary flow reserve or microvascular spasm. This condition, which affects women and men, can markedly impair quality of life and prognosis and represents a substantial cost burden to healthcare systems and individuals alike. In recent years, progress in the diagnosis of myocardial ischemia and the use of tests to investigate functional and structural causes for a reduced coronary flow reserve and microvascular spasm have allowed the identification of an increased number of cases of microvascular angina in everyday clinical practice. Although some of the available anti-anginal drugs may be helpful, treatment of coronary microvascular dysfunction remains a major challenge. The present article discusses the fundamental role that coronary microvascular dysfunction plays in the pathogenesis of ischemic heart disease, the clinical characteristics of patients presenting with microvascular angina, and possible diagnostic and therapeutic strategies.

A randomized, double-blind, placebo-controlled trial to assess the efficAcy and safety of Trimetazidine in patients with angina pectoris having been treated by percutaneous coronary intervention (ATPCI study): Rationale, design, and baseline characteristics

BACKGROUND

About 30% of angina patients have persisting symptoms despite successful revascularization and antianginal therapy. Moreover, in stable patients, percutaneous coronary intervention (PCI) does not improve survival as compared with medical therapy alone. Trimetazidine, an antianginal agent devoid of hemodynamic effect, may help reducing symptoms and improving outcomes after PCI. The ATPCI study is investigating the efficacy and safety of adding trimetazidine to standard-of-care in angina patients who had a recent PCI.

METHODS

ATPCI is a randomized, double-blind, parallel-group, placebo-controlled, event-driven study in patients with coronary artery disease having undergone PCI because of stable angina (elective PCI) or unstable angina/NSTEMI (urgent PCI). After PCI, patients were randomized to trimetazidine (35 mg bid) or placebo on top of standard-of-care including event prevention drugs and antianginal treatment. Patients will be followed for 2 to 4 years. The primary efficacy endpoint is a composite of cardiac death, hospitalization for a cardiac event and recurrence or persistence of angina. Safety events related to trimetazidine use will be monitored.

RESULTS

Recruitment lasted from September 2014 to June 2016. A total of 6007 patients were enrolled (58% and 42% after elective and urgent PCI, respectively). Mean age was 61 years, 77% were males, and median durations of coronary artery disease were 1 and 5 months (if urgent or elective PCI, respectively). Almost all patients received drugs for event prevention and antianginal therapy at baseline.

CONCLUSION

The ATPCI study will shed further light on the management of contemporary angina patients after PCI. Results are expected in 2019.

Endothelial dysfunction as predictor of angina recurrence after successful percutaneous coronary intervention using second generation drug eluting stents

Background The role of endothelial dysfunction in predicting angina recurrence after percutaneous coronary intervention is unknown. Design We assessed the role of peripheral endothelial dysfunction measured by reactive-hyperaemia peripheral-artery tonometry (RH-PAT) in predicting recurrence of angina after percutaneous coronary intervention. Methods We enrolled consecutive patients undergoing percutaneous coronary intervention with second-generation drug-eluting stents. RH-PAT was measured at discharge. The endpoint was repeated coronary angiography for angina recurrence and/or evidence of myocardial ischaemia at follow-up. Patients with in-stent restenosis and/or significant de novo stenosis were defined as having angina with obstructed coronary arteries (AOCA); all other patients as having angina with non-obstructed coronary arteries (ANOCA). Results Among 100 patients (mean age 66.7 ± 10.4 years, 80 (80.0%) male, median follow-up 16 (3-20) months), AOCA occurred in 14 patients (14%), ANOCA in nine patients (9%). Repeated coronary angiography occurred more frequently among patients in the lower RH-PAT index tertile compared with middle and upper tertiles (14 (41.2%) vs. 6 (18.2%) vs. 3 (9.1%), p = 0.006, respectively). ANOCA was more frequent in the lower RH-PAT index tertile compared with middle and upper tertiles. In the multivariate regression analysis, the RH-PAT index only predicted angina recurrence. The receiver operating characteristic curve of the RH-PAT index to predict the angina recurrence demonstrated an area under the curve of 0.79 (95% confidence interval: 0.69-0.89; p < 0.001), with a cut-off value of 1.705, having sensitivity 74% and specificity 70%. Conclusions Non-invasive assessment of peripheral endothelial dysfunction using RH-PAT might help in the prediction of recurrent angina after percutaneous coronary intervention, thus identifying patients who may need more intense pharmacological treatment and risk factor control.

Angina after percutaneous coronary intervention: The need for precision medicine

Persistence or recurrence of angina after successful percutaneous coronary intervention (PCI) represent an important clinical issue involving from one fifth to one third of patients undergoing myocardial revascularization at one-year follow-up. A systematic approach to this syndrome is strongly needed. Precision medicine is particularly important in addressing angina after successful PCI because of the multiple underlying causes. Restenosis or coronary atherosclerosis progression explain symptom recurrence after successful PCI in some patients, while functional causes, including vasomotor abnormalities of epicardial coronary arteries and/or coronary microvascular dysfunction, explain symptoms in the remaining patients. In this review, we summarize the mechanisms of persistent or recurrent angina after PCI, proposing a diagnostic algorithm and a systematic therapeutic approach.

Targeting the dominant mechanism of coronary microvascular dysfunction with intracoronary physiology tests

The coronary microcirculation plays a key role in modulating blood supply to the myocardium. Several factors like myocardial oxygen demands, endothelial and neurogenic conditions determine its function. Although there is available evidence supporting microvascular dysfunction as an important cause of myocardial ischaemia, with both prognostic and symptomatic implications, its diagnosis and management in clinical practice is still relegated to a second plane. Both diagnostic and therapeutic approaches are hampered by the broadness of the concept of microvascular dysfunction, which fails addressing the plurality of mechanisms leading to dysfunction. Normal microcirculatory function requires both structural integrity of the microcirculatory vascular network and preserved signalling pathways ensuring adequate and brisk arteriolar resistance shifts in response to myocardial oxygen demands. Pathological mechanisms affecting these requirements include structural remodelling of microvessels, intraluminal plugging, extravascular compression or vasomotor dysregulation. Importantly, not every diagnostic technique provides evidence on which of these pathophysiological mechanisms is present or predominates in the microcirculation. In this paper we discuss the mechanisms of coronary microvascular dysfunction and the intracoronary tools currently available to detect it, as well as the potential role of each one to unmask the main underlying mechanism.

Prediction of Post Percutaneous Coronary Intervention Myocardial Ischaemia

Following revascularisation the majority of patients obtain symptom relief and improved quality of life. However, myocardial ischaemia may recur or persist in a significant patient subset. Symptom recurrence is usually attributed to inaccurate evaluation of epicardial stenosis, incomplete revascularisation or stent failure and disease progression. However, technological advances with modern imaging and/or physiological evaluation of epicardial plaques have not solved this issue. Conversely, recent clinical studies have shown that abnormal coronary vasomotion and increased myocardial resistance are frequent determinants of post-percutaneous coronary intervention (PCI) myocardial ischaemia. Strategies to enhance prediction of post-PCI angina include proper selection of patients undergoing revascularisation, construction of clinical prediction models, and further invasive evaluation at the time of coronary angiography in those with high likelihood.

Stress Testing After Complete and Successful Coronary Revascularization

BACKGROUND

Noninvasive stress tests play a determinant role in the initial management of patients with chronic angina. Nonetheless, their use in the same patient population is considered inappropriate within 2 years after percutaneous coronary intervention (PCI). Indeed, early abnormal results correlate less well with angiographic control and are attributed to a number of confounding factors. We prospectively assessed prevalence and impact on the quality of life of abnormal stress test results in a highly selected patient population.

METHODS

Patients with no cardiac comorbidities who underwent successful and complete PCI with stenting for typical angina and had an abnormal exercise stress test (EST) under guideline-directed medical treatment were administered the Seattle Angina Questionnaire (SAQ). Clinical evaluation, EST, and the SAQ were repeated at 1, 6, and 12 months after the index PCI.

RESULTS

One hundred ninety-eight patients qualified and were included in the study (mean age, 64 years; 79% men). Although the majority had normal EST results or an increased threshold to angina, at 1 month after the index PCI, 29% of patients still had an abnormal result. At 6 and 12 months, 31% and 29% of patients had abnormal results, respectively. Quality-of-life assessment by the SAQ showed consistent results, with persistent angina in one third of patients. Control angiography documented a critical lesion, attributable to in-stent coronary restenosis, in only 8% of patients.

CONCLUSIONS

When stress testing is systematically performed after PCI, the prevalence of abnormal results is high and is associated with impaired quality of life. Prognostic significance along with the underlying pathophysiological mechanisms of such findings should be investigated.