Paradigm shift to functional angioplasty: new insights for fractional flow reserve- and intravascular ultrasound-guided percutaneous coronary intervention

Clinical effects of physiologic lesion testing in influencing treatment strategy for multi-vessel coronary artery disease

Background

The application of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) in multivessel coronary artery disease (CAD) patients has not been definitively explored. We herein assessed how treatment strategies were decided based on FFR/iFR values in vessels selected clinically. Specifically, we sought to determine whether treatment selection was based on whether the vessel tested was the clinical target stenosis.

Methods

270 consecutive patients with angiographically determined multivessel disease who underwent FFR/iFR testing were included. Patients were classified initially based on their angiographic findings, then re-evaluated from FFR/iFR results (normal or abnormal). Tested lesions were classified into target or non-target lesions based on clinical and non-invasive evaluations.

Results

Abnormal FFR/iFR values were demonstrated in 51.9 % of patients, in whom 51.4 % received coronary stenting (PCI) and 44.3 % had bypass surgery (CABG). With two-vessel CAD patients, medical therapy was preferred when the target lesion was normal (72.6 %), while PCI was preferred when it was abnormal (78.4 %). In non-target lesions, PCI was preferred regardless of FFR/iFR results (78.0 %). With three-vessel CAD patients, CABG was preferred when the target lesion was abnormal (68.5 %), and there was no difference in the selected modality when it was normal. Furthermore, the incidence of tested lesions was higher in the left anterior descending (LAD) compared to other coronary arteries, and two-vessel CAD patients with LAD stenoses were more frequently treated by PCI.

Conclusion

The use of invasive physiologic testing in multivessel CAD patients may alter the preferred treatment strategy, leading to an overall increase in PCI selection.

Target and non-target vessel related events at 10 years post percutaneous coronary intervention

Aims

To define the incidence of events related to the stented vessel (target vessel related events: TVRE) and events related to non-stented vessels (non-target vessel related events: NTVRE) through to 10-year follow-up in patients post-PCI with newer generation drug eluting stents (DES).

Methods and results

The current study is a post-hoc analysis of patient level data from two randomised controlled trials in Germany. Patients older than 18 years with ischemic symptoms or evidence of myocardial ischemia in the presence of ≥ 50% de novo stenosis located in the native coronary vessels were considered eligible. The endpoints of interest were TVRE (a composite of first target vessel myocardial infarction or target vessel revascularization) and NTVRE (a composite of first non-target vessel MI or non-target vessel revascularization) through to 10 years post PCI.

We included 4953 patients in this analysis. Through to 10-years post-PCI, TVRE occurred in 1238 of 4953 patients (cumulative incidence: 25.8%) and NTVRE occurred in 1442 of 4953 patients (cumulative incidence: 30.3%). The majority of TVRE and NTVRE were revascularization events. From 0 to 1 years, the cumulative incidence of TVRE was 15.9% and of NTVRE was 12.3%. From 1 to 10 years, the cumulative incidences of TVRE and NTVRE were 11.2% and 22.4%, respectively.

Conclusion

At 10-year post-PCI with new generation drug eluting stents, events related to remote vessel disease progression account for a higher proportion of events than events related to the stented vessel.

Trial registration

ISAR TEST 4 ClinicalTrials.gov Identifier: NCT00598676. ISAR TEST 5 ClinicalTrials.gov Identifier: NCT00598533.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00392-022-01986-4.

Why the Term MINOCA Does Not Provide Conceptual Clarity for Actionable Decision-Making in Patients with Myocardial Infarction with No Obstructive Coronary Artery Disease

When acute myocardial injury is found in a clinical setting suggestive of myocardial ischemia, the event is labeled as acute myocardial infarction (MI), and the absence of ≥50% coronary stenosis at angiography or greater leads to the working diagnosis of myocardial infarction with non-obstructed coronary arteries (MINOCA). Determining the mechanism of MINOCA and excluding other possible causes for cardiac troponin elevation has notable implications for tailoring secondary prevention measures aimed at improving the overall prognosis of acute MI. The aim of this review is to increase the awareness that establishing the underlying cause of a MINOCA is possible in the vast majority of cases, and that the proper classification of any MI should be pursued. The initial diagnosis of MINOCA can be confirmed or ruled out based on the results of subsequent investigations. Indeed, a comprehensive clinical evaluation at the time of presentation, followed by a dedicated diagnostic work-up, might lead to the identification of the pathophysiologic abnormality leading to MI in almost all cases initially labeled as MINOCA. When a specific cause of acute MI is identified, cardiologists are urged to transition from the "all-inclusive" term "MINOCA" to the proper classification of any MI, as evidence now exists that MINOCA does not provide conceptual clarity for actionable decision-making in MI with angiographically normal coronary arteries.

What Is the Role of Assessing Ischemia to Optimize Therapy and Outcomes for Patients with Stable Angina and Non-obstructed Coronary Arteries?

Ischemic heart disease (IHD) is a leading global cause of ill-health and premature death. Clinical research into IHD is providing new insights into the pathophysiology, epidemiology and treatment of this condition. The major endotypes of IHD include coronary heart disease (CHD) and vasomotor disorders, including microvascular angina and vasospastic angina. Considering unselected patients presenting with stable chest pain, the pre-test probability of CHD is higher in men whereas the pre-test probability of a vasomotor disorder is higher in women. The diagnostic accuracy of diagnostic tests designed to assess coronary anatomy and disease and/or coronary vascular function (functional tests) differ for coronary endotypes. Clinical management should therefore be personalized and take account of sex-related factors. In this review, we consider the definitions of angina and myocardial ischemia. We then appraise the mechanistic links between myocardial ischemia and anginal symptoms and the relative merits of non-invasive and invasive diagnostic tests and related clinical management. Finally, we describe the rationale and importance of stratified medicine of IHD.

Role of fractional flow reserve in the evaluation and management of patients with acute coronary syndrome

PURPOSE OF REVIEW

The aim of this review is to appraise the clinical and prognostic value and pitfalls of FFR across different spectra of ACS presentations and lesion subsets.

RECENT FINDINGS

Preponderance of evidence on this subject is from observational nonrandomized studies with conflicting results and short-term outcomes. Multiple recent studies evaluating the role of FFR-based deferral in non-STE ACS from a potentially culprit lesion have demonstrated poor long-term prognosis as related to future risk of target vessel failure (myocardial infarction/revascularization). The prognostic power of nonischemic FFR seems favorable in clear nonculprit ACS lesions.

SUMMARY

Fractional flow reserve evaluation can be helpful in clinical decision-making for certain subsets of ACS patients and lesions. Definite ACS-producing lesions should not be evaluated using FFR due to altered pathophysiology and distinct mechanisms underlying the disease process. In uncertain culprit lesions, FFR may be useful with complementary intracoronary imaging.

Improving myocardial fractional flow reserve in coronary atherosclerosis via CX37 gene silence: a preclinical validation study in pigs

OBJECTIVES

The purpose of this study was to evaluate the effect of CX37 gene silence on myocardial fractional flow reserve (FFR).

METHODS

A total of 90 male pigs were randomly divided into saline, mock and 3 different doses (5, 10 and 20 µl) of CX37 viral suspension groups that could induce coronary plaque formation with high-fat diet. After performing myocardial FFR by intravascular ultrasound, different doses of CX37 viral suspension, saline and mock small interfering RNA (siRNA) were transfected into the related coronary. The FFR, the myocardial enzymes and the cardiac structures and functions of the pigs were detected at baseline, 4th, 8th and 12th week after transfection, respectively.

RESULTS

Repeated measures analysis of variance comparison showed that the difference in the FFR among the 5 groups was statistically significant (F = 27.0, P < 0.01). Post hoc analysis showed that FFR were highest in the siRNA CX37 group (20 µl), followed by the siRNA CX37 group (10 µl) and the siRNA CX37 group (5 µl), and lowest in the mock and saline groups. Left ventricular end-diastolic diameter was significantly smaller and ejection fraction was obviously higher in the 3 siRNA CX37 groups compared with the untreated groups.

CONCLUSIONS

Our study showed that FFR levels increased along with decreased doses of siRNA CX37 lentivirus, indicating that siRNA CX37 lentivirus may reduce the risk of coronary atherosclerosis and provide a potential approach to treat coronary heart disease.

A Test in Context: Fractional Flow Reserve: Accuracy, Prognostic Implications, and Limitations

Fractional flow reserve (FFR) is an invasive procedure used during coronary angiography to determine the functional significance of coronary stenoses. Its use is particularly helpful in intermediate or angiographically ambiguous lesions in the absence of noninvasive functional studies. Randomized clinical trials have reported improved clinical outcomes with the use of FFR to guide coronary revascularization, including a reduction in cardiac death or myocardial infarction, as well as costs, with an FFR-based strategy compared with a conventional angiography-based approach. Current societal guidelines provide a Class II, Level of Evidence: A recommendation to perform FFR in angiographically intermediate stenoses in the absence of stress testing or in the presence of discordant stress test results and angiographic findings. However, despite the relative ease of use of FFR, multiple technical factors can impair its accuracy, and attention to detail is critical when performing the test. This review focuses on the fundamental basics of FFR testing, clinical evidence, and limitations.

Catheter-based functional metrics of the coronary circulation

In patients with stable chest pain, decision making about treatment strategy should be based on anatomical and functional information on the coronary circulation. Traditionally, the functional data are obtained by non-invasive testing which aims at detecting and localizing 'myocardial ischemia.' Yet, the diagnostic accuracy of diagnostic testing is over-rated in the literature, so that in clinical practice, a sizable proportion of patients undergo a coronary angiogram without prior useful functional information. Therefore, several methods have been developed to obtain similar information in the catheterization laboratory. Here we review briefly some of these methods. Some of them are used routinely in clinical practice, and others are under development.

Prinzmetals angina presenting with non critical lesion with normal FFR -to stent or not to stent

Variant angina also called Prinzmetals angina is an enigma characterized by transient circadian symptoms of chest pain associated with ECG changes. The patient is symptom free with normal ECG and echo during symptom free periods. We present a case associated with transient ST-segment elevation with non critical lesion with normal FFR.

Competitive Coronary Flow between the Native Left Anterior Descending Artery and Left Internal Mammary Artery Graft: Is It a Surrogate Angiographic Marker of Over-or-Unnecessary Revascularization Decision in Daily Practice?

Overdiagnosis and overtreatment are often thought of as relatively recent phenomena in modern medicine, influenced by a contemporary combination of technology, specialization, payment models, marketing, and supply-related demand. Several investigators have reported discrepancies between the angiographic and functional severity of coronary angiographic stenosis. However, the visual anatomic assessment of the coronary lesion severity continues in daily practice. We evaluated the consecutive all coronary angiograms performed between January 2015 and December 2015 and examined only patients who had previous coronary artery bypass grafting (CABG) to analyze the cases with regard to presence of the competitive flow (CF) between the native left anterior descending coronary artery (LAD) and left internal mammary artery (LIMA) graft. A total of 8,248 diagnostic coronary angiographies were performed between January 2015 and December 2015 at our facility. Of these, 886 coronary angiographies of CABG patients were detected. Whereas LIMA graft occlusion detected in 19 patient (2.1%), the LIMA-LAD CF rate was found in 86 (9.7%) CABG patients. The angiographic severity of the LAD stenosis in CF group evaluated as mild in 20 (25%), moderate in 61 (70%), and severe coronary artery disease in 4 (5%) patients. Our results showed that there is 9.7% rate of LIMA-LAD CF. Therefore, some unnecessary coronary stenting or CABG procedures might have been performed due to limited use of functional testing for clinical decision making. The functional angiography should play a more prominent role in catheterization laboratories as recommended by current revascularization guidelines to prevent overdiagnosis, misdiagnosis, or incorrect treatment decisions.

Prognostic Determinants of Coronary Atherosclerosis in Stable Ischemic Heart Disease

Risk stratification in patients with stable ischemic heart disease is essential to guide treatment decisions. In this regard, whether coronary anatomy, physiology, or plaque morphology is the best determinant of prognosis (and driver an effective therapeutic risk reduction) remains one of the greatest ongoing debates in cardiology. In the present report, we review the evidence for each of these characteristics and explore potential algorithms that may enable a practical diagnostic and therapeutic strategy for the management of patients with stable ischemic heart disease.

The Concept of Functional Percutaneous Coronary Intervention: Why Physiologic Lesion Assessment Is Integral to Coronary Angiography

The gold standard for assessing the severity of coronary stenoses has been coronary angiography. However, multicenter randomized clinical trials have demonstrated that treatment decisions based on angiography alone do not guarantee benefit to patients. Fractional flow reserve provides physiologic lesion assessment of coronary stenoses. The use of physiology improves clinical outcomes when used for decision making for coronary revascularization. In the era of increased scrutiny of appropriateness of cardiac catheterization and percutaneous coronary intervention, the use of physiologic assessment of the severity of coronary stenoses should be considered an integral adjunct to the anatomic evaluation provided by the coronary angiogram.

Association of Lower Fractional Flow Reserve Values With Higher Risk of Adverse Cardiac Events for Lesions Deferred Revascularization Among Patients With Acute Coronary Syndrome

Background

The safety of deferring revascularization based on fractional flow reserve (FFR) during acute coronary syndrome (ACS) is unclear. We evaluated the association of FFR and adverse cardiac events among patients with coronary lesions deferred revascularization based on FFR in the setting of ACS versus non-ACS.

Methods and Results

The study population (674 patients; 816 lesions) was divided into ACS (n=334) and non-ACS (n=340) groups based on the diagnosis when revascularization was deferred based on FFR values >0.80 between October 2002 and July 2010. The association and interaction between FFR and clinical outcomes was evaluated using Cox proportional hazards models within each group (mean follow-up of 4.5±2.1 years). Subsequent revascularization of a deferred lesion was classified as a deferred lesion intervention (DLI), whereas the composite of DLI or myocardial infarction (MI) attributed to a deferred lesion was designated as deferred lesion failure (DLF). In the non-ACS group, lower FFR values were not associated with any increase in adverse cardiac events. In the ACS group, every 0.01 decrease in FFR was associated with a significantly higher rate of cardiovascular death, MI, or DLI (hazard ratio [HR], 1.08; 95% confidence interval [CI], 1.03 to 1.12), MI or DLI (HR, 1.09; 95% CI: 1.04 to 1.14), DLF (HR, 1.12; 95% CI, 1.06 to 1.18), MI (HR, 1.07; 95% CI, 1.00 to 1.14), and DLI (HR, 1.12; 95% CI, 1.06 to 1.18).

Conclusion

Lower FFR values among ACS patients with coronary lesions deferred revascularization based on FFR are associated with a significantly higher rate of adverse cardiac events. This association was not observed in non-ACS patients.

Aetiological diagnosis of middle-aged and elderly cryptogenic ischaemic cerebral vascular disease

Although tremendous efforts have been made to explore the potential aetiologies of cryptogenic ischaemic cerebral vascular disease (CICVD), it remains a great challenge for neurologists to get a comprehensive picture of CICVD across the world. Part of the reason why is that the vast majority of studies have focussed on CICVD in young stroke patients while the underlying causes of CICVD in middle-aged or elderly stroke population have not been fully investigated. The focus of this paper has been dedicated to review the different studies that explore the aetiologies of CICVD cases in this patient population. While there is a set of heterogeneous causes that can lead to CICVD in middle-aged and elderly patients, our review reveals that emboli originated from or across occult places within the heart or produced by transient arrhythmias could possibly be the main culprit. Dislodged aortic plaques might also account for certain CICVD cases and in fewer cases, hereditary arteriopathy and thrombophilia can also play a role. The aforementioned factors have similar roles in middle-aged and elderly CICVD patients as in their younger counterparts. However, more studies are needed to explore the role of these factors in older patients.

Clinical usefulness and cost effectiveness of fractional flow reserve among Indian patients (FIND study)

OBJECTIVES

To study the clinical usefulness, cost benefit, and medium term outcome of fractional flow reserve (FFR) based management of coronary artery disease of intermediate severity.

BACKGROUND

In spite of the advantages of FFR there is paucity of data in Indian population who have frequent diffuse, small and multivessel disease where it would probably be more beneficial in terms of cost and outcome.

METHODS

The treating cardiologist's management decision with both FFR and angiographic data was compared with that of a reviewing cardiologist decision based on a retrospective analysis of angiogram alone.

RESULTS

Eighty-one vessels with intermediate lesions in 59 patients required 26 stents lesser when FFR data was added to the angiogram. The concordance of management decision was about 58% which means that >40% of intermediate lesions would be misclassified as significant based on angiography alone. There were no major events at a mean follow up of 11 ± 5 months. The net cost benefit in favor of FFR based management was INR 8,57,600 (USD 15,600) in our centre.

CONCLUSION

Indians with more severe form of CAD benefit from a FFR based management plan for intermediate lesions, both clinically and economically. © 2014 Wiley Periodicals, Inc.

Fractional flow reserve-guided coronary bypass surgery: should surgeons use it?

PURPOSE OF REVIEW

Physiology-based evaluation in stable ischemic heart disease is transforming percutaneous cardiovascular intervention (PCI). Fractional flow reserve (FFR)-guided PCI is associated with more appropriate and beneficial outcomes at lower costs. The surgical community can no longer ignore this development. We review evidence for the rationale, practicality and appropriateness of FFR-guided coronary artery bypass grafting (CABG), as compared with the current conventional, anatomy-based strategy for surgical revascularization.

RECENT FINDINGS

Physiologic evaluation links the nature (anatomic or functional) of coronary stenoses to the perfused myocardium supplied by the target vessel and challenges the use of anatomy as the sole criterion for revascularization intervention. In CABG, a functional perfusion deficit/ischemia identifies myocardial territories that would physiologically benefit from revascularization by grafting beyond the functional stenosis. Conversely, deliberately not grafting beyond an anatomic stenosis would dramatically change the procedure of CABG. Recent studies of functionally guided revascularization (PCI or CABG) support this approach, while recent trials of PCI vs. CABG demonstrated a late survival advantage with anatomy-based CABG. Finally, new intraoperative imaging technologies are elucidating the physiologic consequences of surgical revascularization in real time, yielding insights into resolving this dilemma.

SUMMARY

Physiologic-based revascularization is challenging our thinking about the historic strategy for CABG. Understanding better the physiologic consequences of revascularization will drive the evolution of CABG in the future.

Myocardial ischemia is a key factor in the management of stable coronary artery disease

Previous studies demonstrated that coronary revascularization, especially percutaneous coronary intervention (PCI), does not significantly decrease the incidence of cardiac death or myocardial infarction in patients with stable coronary artery disease. Many studies using myocardial perfusion imaging (MPI) showed that, for patients with moderate to severe ischemia, revascularization is the preferred therapy for survival benefit, whereas for patients with no to mild ischemia, medical therapy is the main choice, and revascularization is associated with increased mortality. There is some evidence that revascularization in patients with no or mild ischemia is likely to result in worsened ischemia, which is associated with increased mortality. Studies using fractional flow reserve (FFR) demonstrate that ischemia-guided PCI is superior to angiography-guided PCI, and the presence of ischemia is the key to decision-making for PCI. Complementary use of noninvasive MPI and invasive FFR would be important to compensate for each method's limitations. Recent studies of appropriateness criteria showed that, although PCI in the acute setting and coronary bypass surgery are properly performed in most patients, PCI in the non-acute setting is often inappropriate, and stress testing to identify myocardial ischemia is performed in less than half of patients. Also, some studies suggested that revascularization in an inappropriate setting is not associated with improved prognosis. Taken together, the presence and the extent of myocardial ischemia is a key factor in the management of patients with stable coronary artery disease, and coronary revascularization in the absence of myocardial ischemia is associated with worsened prognosis.

Quantitative Computed Tomographic Coronary Angiography

Background—

Coronary lesions with a diameter narrowing ≥50% on visual computed tomographic coronary angiography (CTCA) are generally considered for referral to invasive coronary angiography. However, similar to invasive coronary angiography, visual CTCA is often inaccurate in detecting functionally significant coronary lesions. We sought to compare the diagnostic performance of quantitative CTCA with visual CTCA for the detection of functionally significant coronary lesions using fractional flow reserve (FFR) as the reference standard.

Methods and Results—

CTCA and FFR measurements were obtained in 99 symptomatic patients. In total, 144 coronary lesions detected on CTCA were visually graded for stenosis severity. Quantitative CTCA measurements included lesion length, minimal area diameter, % area stenosis, minimal lumen diameter, % diameter stenosis, and plaque burden [(vessel area−lumen area)/vessel area×100]. Optimal cutoff values of CTCA-derived parameters were determined, and their diagnostic accuracy for the detection of flow-limiting coronary lesions (FFR ≤0.80) was compared with visual CTCA. FFR was ≤0.80 in 54 of 144 (38%) coronary lesions. Optimal cutoff values to predict flow-limiting coronary lesion were 10 mm for lesion length, 1.8 mm 2 for minimal area diameter, 73% for % area stenosis, 1.5 mm for minimal lumen diameter, 48% for % diameter stenosis, and 76% for plaque burden. No significant difference in sensitivity was found between visual CTCA and quantitative CTCA parameters ( P >0.05). The specificity of visual CTCA (42%; 95% confidence interval [CI], 31%–54%) was lower than that of minimal area diameter (68%; 95% CI, 57%–77%; P =0.001), % area stenosis (76%; 95% CI, 65%–84%; P <0.001), minimal lumen diameter (67%; 95% CI, 55%–76%; P =0.001), % diameter stenosis (72%; 95% CI, 62%–80%; P <0.001), and plaque burden (63%; 95% CI, 52%–73%; P =0.004). The specificity of lesion length was comparable with that of visual CTCA.

Conclusions—

Quantitative CTCA improves the prediction of functionally significant coronary lesions compared with visual CTCA assessment but remains insufficient. Functional assessment is still required in lesions of moderate stenosis to accurately detect impaired FFR.

Vasoactive and Antiarrhythmic Drugs During Percutaneous Coronary Intervention

The objective in percutaneous coronary intervention (PCI) is to treat flow-limiting atherothrombotic coronary plaques mechanically. Many types of antithrombotic drugs are used to prevent ischemic complications during manipulation of catheters, guidewires, balloons, and stents in coronary arteries while minimizing the risk of bleeding. However, many other types of pharmacologic agents are also used to facilitate PCI. This review focuses on the most commonly used adjunct drugs during PCI. In addition, a recommendation of which drugs should be stopped or interrupted in patients undergoing PCI is provided.

Comparison of effectiveness of high-dose intracoronary adenosine versus intravenous administration on the assessment of fractional flow reserve in patients with coronary heart disease

Intravenous adenosine is considered the drug of choice to obtain maximum hyperemia in the measurement of the fractional flow reserve (FFR). However, comparative studies performed between intravenous and intracoronary administration have not used high doses of intracoronary adenosine. The present study compared the efficacy and safety of high doses of intracoronary adenosine to intravenous administration when calculating the FFR. Intracoronary bolus doses of 60, 180, 300, and 600 μg adenosine were compared to an intravenous administration of 140 μg/kg/min, 200 μg/kg/min, and 140 μg/kg/min plus an intracoronary bolus of 120 μg. All the cases were performed using the radial approach. FFR was assessed in 102 patients with 108 intermediate lesions by an intracoronary pressure wire. The intracoronary dose of 60 μg was associated with a significantly greater FFR compared to the intravenous infusion (0.02 ± 0.03, p = 0.001). The intracoronary doses of 300 (-0.01 ± 0.00; p = 0.006) and 600 μg (-0.02 ± 0.00; p <0.0005) were significantly associated with a smaller FFR compared to the intravenous infusion. An intracoronary dose of 600 μg revealed a significantly greater percentage of lesions with an FFR <0.80 compared to intravenous infusion at 140 μg/kg/min (37.6 vs 31.5%; p <0.05) and 200 μg/kg/min (37.6 vs 32.4%; p <0.05) and compared to intracoronary doses of 60 (26.9%) and 180 μg (31.5%). In conclusion, an intracoronary bolus dose >300 μg can be equal to or more effective than an intravenous infusion of adenosine in achieving maximum hyperemia when calculating the FFR. Its use could simplify these procedures without having an effect on safety.

Triple, simultaneous, very late coronary stent thrombosis

Coronary artery stent thrombosis is an uncommon but potentially catastrophic complication. The risk of very late stent thrombosis (VLST) raises important safety issues regarding the first generation of drug-eluting stents (DES). Although several complex mechanisms for VLST have been suggested and various predictors have been described, its pathophysiology is not completely understood and it is not known whether longer-term dual antiplatelet therapy reduces the risk. We present a rare case of simultaneous very late DES thrombosis in the three vascular territories, following discontinuation of antiplatelet therapy seven years after stent placement, presenting as cardiogenic shock.