Diagnosing and Treating Coronary Microvascular Dysfunction

Angiography Doesn't Tell You the Whole Story

Approximately 112 million people globally are affected by angina and undergo coronary angiography, the primary diagnostic test for angina.1 Unfortunately, angiography is limited to assessing the epicardial arteries and cannot assess the microcirculation, which is largely responsible for the regulation and distribution of blood flow to the myocardium.2 Additionally, too often patients with ischemia with non-obstructive coronary arteries (INOCA) on angiography remain undiagnosed.3 About 40-60% of chronic coronary syndrome (CCS) patients undergoing angiography have INOCA, and a large proportion of these patients may have coronary microvascular dysfunction (CMD).4,5 Proper diagnosis of CMD and treatment is the only way to improve outcomes in these patients at high risk for major adverse cardiac events (MACE).4

Prevalence and Purpose of Diagnosing Coronary Microvascular Dysfunction (CMD)

Prof. Divaka Perera, Consultant Cardiologist, London, UK

Diagnosing The Underlying Cause Of Chest Pain Can Be Challenging

 

Ischemic heart disease continues to be the leading cause of death globally.6  Yet chest pain—while often ischemic in nature—could have many etiologies, as illustrated.7 When chest pain is caused by ischemia (angina), proper management depends on accurately identifying and treating the underlying cause of angina.

Chest pain can have many underlying causes
Marinescu MA, Löffler Al, Ouellette M, et al. Coronary microvascular dysfunction and microvascular angina: a systematic review of therapies. JACC Cardiovasc Imaging. 2015; 8:210-220. Kunadian V, Chieffo A, Cmici PG, et al. EAPCI Expert Consensus Document. EHJ. 2020; 0:1-21.

Structural and functional causes of recurrent or persistent angina despite non-obstructive coronary artery disease.8

RECURRENT OR PERSISTENT ANGINA

Structural Causes8

  • In-stent restenosis
  • Stent thrombosis
  • Progression of atherosclerotic disease in other segments
  • Incomplete revascularization
  • Diffuse atherosclerotic disease without focal stenosis
  • Presence of myocardial bridges

Functional Causes8

  • Coronary microvascular dysfunction
  • Epicardial vasospasm
  • Stent-related mechanical stretch of the arterial wall

The Majority Of Patients In The Cath Lab Are Found To Have No Obstructive Coronary Artery Disease

Only 41% of patients assessed for angina are found to have obstructive chronic coronary artery disease.4 The majority (59%) have no angiographic abnormalities,4 but still have symptoms of a coronary disorder.9
 

20-30% of patients experience recurrent angina in 1 year after percutaneous coronary intervention (PCI).10
 

Most angiograms yield no coronary artery disease
Patel et al. Low diagnostic yield of elective coronary angiography. NEJM 2010.
20-30% of patients experience recurrent angina in 1 year after percutaneous coronary intervention (PCI)


INOCA patients with persistent angina frequently remain underdiagnosed. Without a clear diagnosis and treatment, this may result in recurrent hospitalizations, poor functional health, and adverse cardiovascular outcomes.11

Up to 50-65% of patients who have angina but non-obstructive CAD are believed to have coronary microvascular dysfunction (CMD).7

Left Undiagnosed And Untreated, Cmd Can Have A Major Impact On Both Patients And Healthcare Systems

The microcirculation carries far more myocardial blood volume compared to the epicardial arteries. CMD can be defined as impaired CFR in the absence of epicardial obstructive CAD—i.e., downstream vasomotor dysfunction.12
 

INOCA Is Not Benign: The Impact on Clinical Outcomes

Patients with INOCA, including those diagnosed with CMD, have an increase in major adverse cardiac events (MACE) including:

  • Myocardial infarction13
  • Stroke13
  • Diastolic dysfunction12 and heart failure12,13
  • Cardiovascular death13
  • Cardiac death12
  • All-cause mortality13

Coronary Flow Reserve Associated with MACE Risks12

Reduced coronary flow reserve is associated with adverse events
Image adapted from Taqueti et al, J Am Coll Cardiol 201812

Clinical Spectrum of CMD

MACE risk increases with CMD severity
Image adapted from Taqueti et al, J Am Coll Cardiol 201812

The clinical spectrum of CMD may be characterized by three factors:12

  • The severity of CMD
  • The degree of atherosclerosis
  • Any associated clinical risks

The Impact on Healthcare Costs, Cath Labs, and Patients

$2,100 - $7,300

INOCA frequently impacts patient quality of life (QOL) and consumes significant health care expenditures.14,15 With multiple evaluations and frequent hospitalization,14,15 each additional hospitalization can add $2,100 (the Netherlands) to $7,300 (the U.S.) in healthcare costs.16

Nevertheless, it is possible to accurately diagnose patients on their first visit to the cath lab and to provide effective treatment.

References

  1. Kunadian V, Chieffo A, Camici PG, et al. An EAPCI Expert Consensus Document on Ischaemic with Non-Obstructive Coronary Arteries in Collaboration with European Society of Cardiology Working Group on Coronary Pathophysiology & Microcirculation Endorsed by Coronary Vasomotor Disorders International Study Group. European Heart Journal. 2020; 0:1-21.
  2. Taqueti VR, Di Carli MF. Coronary microvascular disease pathogenic mechanisms and therapeutic options: JACC state-of-the-art review. J Am Coll Cardiol. 2018;72:2625–2641. doi:10.1016/j.jacc.2018.09.042.
  3. Jespersen L, Hvelplund A, Abildstrøm SZ, et al. Stable angina pectoris with no obstructive coronary artery disease is associated with increased risks of major adverse cardiovascular events. Eur Heart J. 2012;33:734-744. doi:10.1093/eurheartj/ehr331.
  4. Patel MR , Peterson ED , Dai D , et al. Low diagnostic yield of elective coronary angiography. N Engl J Med. 2010;362:886-895. doi:10.1056/NEJMoa0907272.
  5. Maas A, et al. Microvascular angina: diagnosis, assessment, and treatment. EMJ Int Cardiol. 2019; 7[Suppl 1]2-17.
  6. Wang H, Naghavi M, Allen C, et al. Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980–2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet 2016;388:1459-544.
  7. Marinescu MA, Löffler AI, Ouellette M, et al. Coronary microvascular dysfunction and microvascular angina: a systematic review of therapies. JACC Cardiovasc Imaging. 2015;8:210-220. doi:10.1016/j.jcmg.2014.12.008.
  8. Niccoli G, Montone RA, Lanza GA, et al. Angina after percutaneous coronary intervention: the need for precision medicine. Int J Cardiol. 2017;248:14-19. doi: 10.1016/j.ijcard.2017.07.105.
  9. Ford TJ, Berry C. How to diagnose and manage angina without obstructive coronary artery disease: lessons from the British Heart Foundation CorMicA Trial. Interv Cardiol Rev. 2019;14(2):76-82.
  10. Jeremias A. Blinded Physiological Assessment of Residual Ischemia after Successful Angiographic PCI. ACC 2019.
  11. Lee B, Lim H, Fearon WF, et al. Invasive evaluation of patients with angina in the absence of obstructive coronary artery disease. Circulation. 2015;131:1054–1060.
  12. Taqueti VR, Di Carli MF. Coronary microvascular disease pathogenic mechanisms and therapeutic options: JACC state-of-the-art review. J Am Coll Cardiol. 2018;72:2625–2641. doi:10.1016/j.jacc.2018.09.042.
  13. Jespersen L, Hvelplund A, Abildstrøm SZ, et al. Stable angina pectoris with no obstructive coronary artery disease is associated with increased risks of major adverse cardiovascular events. Eur Heart J. 2012;33:734-744. doi:10.1093/eurheartj/ehr331.
  14. Lee B, Lim H, Fearon WF, et al. Invasive evaluation of patients with angina in the absence of obstructive coronary artery disease. Circulation. 2015;131:1054–1060.
  15. Reriani M, Flammer AJ, Duhé J, et al. Coronary endothelial function testing may improve long-term quality of life in subjects with microvascular coronary endothelial dysfunction. Open Heart. 2019;6:e000870. doi: 10.1136/openhrt-2018-000870.
  16. Omerovic E. FFR-Guided Complete Revascularization During Primary Angioplasty: Effects on Societal Costs. EuroPCR 2017.

MAT-2006712 v1.0

Important Safety Information

Coroventis‡ CoroFlow Cardiovascular System

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Indications: CoroFlow is indicated to provide hemodynamic information for use in the diagnosis of patients with cardiovascular diseases.

CoroFlow is intended for use in catheterization and related cardiovascular specialty laboratories to compute and display various physiological parameters based on the output from one or more measuring devices.

Contraindications: The system has no patient alarm functions. Do not use for cardiac/vital signs monitoring.

Warnings:

  • If CoroFlow is used together with 3rd party infusion catheters for assessment of Absolute Flow and Resistance, ensure that the maximum infusion rate per manufacturers instruction is not exceeded or vessel injury may occur.
  • Do not use the CoroFlow measurement system if there is reason to believe the system's security has been compromised or if the system was unaccounted for a period of time (i.e. misappropriated, modified or tampered with).
  • Do not leave the CoroFlow measurement system unattended when logged in as a PC Administrator
  • To protect the privacy and security of sensitive information, including electronic protected health information (EPHI), and to protect the integrity of the system itself, the system should be located in a physically secure, access-controlled environment.
  • To protect the privacy and security of sensitive information, including electronic protected health information (EPHI), the PC on to which CoroFlow is installed must be configured according to the Installation Instructions in this manual. Failure to configure the PC correctly may result in increased risk for unauthorized release of protected health information. Windows settings include:
    • Activation and configuration of restricted user Access
    • Activation of Windows Firewall and blocking of network connections
    • Activation of Windows Bitlocker drive encryption
    • Activation of Windows Secure Boot
    • Activation of Windows Anti-Virus scanning
    • Activation of Windows update
  • Use of this equipment adjacent to or stacked with other equipment should be avoided because it could result in improper operation. If such use is necessary, this equipment and the other equipment should be observed to verify that they are operating normally.
  • Use of accessories, transducers and cables other than those specified or provided by Coroventis could result in increased electromagnetic emissions or decreased electromagnetic immunity of this equipment and result in improper operation.
  • Portable RF communications equipment (including peripherals such as antenna cables and external antennas) should be used no closer than 30 cm (12 inches) to any part of CoroFlow, including cables specified by Coroventis. Otherwise, degradation of the performance of this equipment could result.

 

Precautions:

  • The PC and CoroHub‡ shall not be placed within the patient environment (1.5 m from patient).
  • For operation of other devices used in conjunction with CoroFlow consult the IFU for each of these devices for details on indication, handling and safety information.
  • It is recommended to ensure local routines for data backup of stored recordings. CoroFlow does not create backup of stored data.
  • Always check minimum performance requirement on PC to ensure compatibility with CoroFlow.
  • It is recommended to install CoroFlow on a PC with backup battery to avoid interruption in case of power failure.
  • Always manually review and confirm valid cursor positions and detected heart beats.
  • Ensure that Pa and Pd pressure waveforms are aligned in phase and offset after equalization, or indices can be mis-calculated.
  • Confirm that the correct Wi-Box is selected by manually matching the Wi-Box ID number with the Wi-Box in the lab.
  • Changing parameter settings outside of default values may affect measurement performance, only for research purposes.
  • Only to be used by healthcare professionals
  • Using a network location to store data may cause previously unidentified risks if the network malfunctions
  • The assembly of medical electrical systems and modifications during the actual service life require evaluation to the requirements according to IEC 60601-1 standard series.
  • CoroHub does not have any serviceable parts and require no field maintenance. No modification or tampering with CoroHub is permitted.
  • CoroHub shall not be immersed in liquid.
  • CoroHub shall not be used if it has been subject to damage
  • Direct connection to a non-secure network, like the internet, may interfere with correct operation and/or result in inappropriate access to patient information. Furthermore, it should be noted that reconfiguring a used network may lead to inability to import patient as well as export examination data, ultimately leading to a risk of loss of patient and examination data. To avoid this problem Coroventis recommends verifying network settings in the system setup after each change.

PressureWire™ X Guidewire

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Indications: The PressureWire™ X Guidewire is indicated to direct a catheter through a blood vessel and to measure physiological parameters in the heart and in the coronary and peripheral blood vessels. Physiological parameters include blood pressure. The PressureWire™ X Guidewire can also measure blood temperature.

Contraindications: This guidewire is contraindicated for use in the cerebral vasculature.

Warnings:

  • No modification of this device is allowed.
  • The PressureWire™ X Guidewire is supplied sterile. Discard the guidewire if the pouch is opened or damaged, compromising the sterile barrier. The guidewire is designed for single use only and shall not be reused or resterilized. Adverse effects of using a non-sterile or resterilized guidewire may include, but are not limited to:
    • Local and/or systemic infection
    • Mechanical damage
    • Inaccurate readings
  • Observe all guidewire movements. Whenever the guidewire is moved or torqued, the tip movement should be examined under fluoroscopy. Never push, withdraw, or torque the guidewire if it meets resistance or without observing corresponding movement of the tip, otherwise vessel/ventricle trauma may occur.
  • Torquing or excessive manipulation of the guidewire in a sharp bend, against resistance, or repeated attempts to cross a total vessel occlusion may:
    • Cause dissection or perforation of blood vessels
    • Cause vessel spasm
    • Damage and/or fracture the guidewire
  • When introducing the guidewire, flush the catheter and administer anticoagulation as for a standard catheterization procedure or clotting may occur.
  • Do not use the guidewire in the ventricles if the patient has a prosthetic mechanical or biological valve. It may result in damage to both the prosthesis and the guidewire, which may cause injury or death.
  • Use of the PressureWire™ X Guidewire in conjunction with interventional devices with a short rapid exchange may result in a folded or fractured guidewire.
  • High frequency surgical devices must not be used on a patient at the same time as the guidewire.


Precautions:

  • The PressureWire™ X Guidewire is a delicate instrument and should be handled carefully.
  • Make sure that the transmitter is kept dry to ensure accurate pressure and/or temperature readings. Inaccurate readings may necessitate device replacement.
  • Do not use the guidewire in conjunction with atherectomy catheters. It may damage the guidewire.
  • Do not withdraw or manipulate the guidewire in a sharp-edged object. It may result in abrasion of the guidewire coating.
  • Factors that may affect the accuracy of the diagnostic information include, but are not limited to:
    • Improper placement of the aortic pressure sensor.
    • Failure to achieve maximum coronary and myocardial hyperemia in FFR procedures
    • Blood flow affected by the position of interventional devices, such as balloon catheters.
  • Guidewire readings may be affected by defibrillation. Rezero the guidewire after defibrillation use.
  • Do not measure pressure when the guidewire sensor element is in a sharp bend or in contact with atrial or ventricular walls. It might result in pressure artifacts.
  • Do not use the PressureWire™ X Guidewire together with another guidewire, for so called jailed wire technique, due to difficulty in guidewire withdrawal and possible guidewire entrapment.
  • Store at room temperature in a dry and dark place.


Potential Adverse Events: Potential complications which may be encountered during all catheterization procedures include, but are not limited to: vessel dissection or occlusion, perforation, embolus, spasm, local and/or systemic infection, pneumothorax, congestive heart failure, myocardial infarction, hypotension, chest pain, renal insufficiency, serious arrhythmias, or death.

MAT-2103602 v1.0