3D Angiography Helps Identify Hidden Coronary Lesions
In Symptomatic Patients, 3D-QCA Can Help Pinpoint Potentially Problematic Blockages and Reduce Treatment Variation
Three-dimensional imaging known as 3D quantitative coronary angiography (3D-QCA) accurately identifies hard-to-see coronary artery lesions that merit further evaluation, according to the IQ-CATEGORIZE Lesions Study presented as a late-breaking clinical trial at the SCAI 2014 Scientific Sessions.
In patients with symptoms or tests suggestive of coronary artery disease but visibly underwhelming disease on angiography, variation in how the angiogram is interpreted can lead to wide variation in treatment, and concerns of over- or under-treatment. This new study evaluates reliability of 3D-QCA as a simple tool to determine lesion severity.
Interventional cardiologists routinely use the caliber of the coronary catheter to determine stent size. In 3D-QCA, a 3D image is created in a similar way, by using the catheter’s size in two or more angled views to create a proportionate 3D image.
To evaluate 3D-QCA’s accuracy, researchers reviewed 131 suspicious lesions in 79 patients. They compared average minimum coronary channel (or luminal) diameter (MLD) from two angulated views to the in-lesion percent plaque area stenosis (%PAS), a proven and highly accurate measure taken by intravascular coronary ultrasound (IVUS).
Prior studies using IVUS have established %PAS >67% in left main arteries and >70% in non-left main arteries as accurate measures of blockage severity. However, %PAS is less commonly used than other severity measures because it requires additional equipment to be passed down an artery. 3D-QCA has potential advantages, because its 3D images are constructed using standard coronary angiogram images without need for additional imaging or equipment.
In this study, researchers used a 6 French (Fr) = 2mm catheter severity cutoff for small (2.6-3.0mm) and medium-sized (3.1-4.5mm) vessels, and an 8 Fr or 2.67mm cutoff for left main or large (>4.5mm) vessels. They found average MLDs less than the cutoffs measured by 3D-QCA were highly predictive of %PAS results. In small and medium vessels, 3D-QCA was highly accurate in predicting severe %PAS >70%, which is likely to indicate severe disease (93% accuracy in small vessels and 97% accuracy in medium vessels). In left main and large vessels, 3D-QCA reliably distinguished severe %PAS >67% and >70% (94% accuracy in left main and 92% accuracy in large vessels).
“In symptomatic patients, 3D-QCA using the cutoffs established in this study helps determine the location of relevant severe suspicious blockages that may warrant treatment,” said Charles Laham, MD, FACC, FRCPC, FSCAI, principal investigator of the study. “3D-QCA appears to be a simple yet reliable tool to help interventional cardiologists distinguish which occult lesions should be further evaluated. The technique can help improve patient care, while reducing variation in care.”
Dr. Laham reports no conflicts of interest.
Dr. Laham presented “3Dimensional Quantitative Coronary Angiography using Coronary Catheters as Objective Markers Reliably Unmasks Severe Occult Stenosis in Diffusely Diseased Vessels: New Results from the IQ-CATEGORIZE Lesions Study,” on Friday, May 30, 2014, at 2:00 pm.
ORBIT II Study One-Year Results Demonstrate Orbital Atherectomy System Improves Stent Deployment and Long-Term Outcomes in High-Risk Patients
After one year, patients treated with orbital atherectomy were less likely to require a repeat procedure to reopen their vessel or suffer a heart attack or death compared to other published trials in patients with heavily calcified arteries. The new results from the ORBIT II study were presented as a late-breaking clinical trial at the SCAI 2014 Scientific Sessions.
The ORBIT II study is the first to exclusively investigate severely calcified lesions, and it studied high-risk patients that are usually excluded from large clinical trials, including those on dialysis or with low left ventricular ejection fraction (>25%).
“Often patients with calcified lesions are more difficult to treat because the calcium can interfere with proper stent placement,” said Jeffrey Chambers, MD, FSCAI, director of the cardiac catheterization laboratory, Mercy Hospital, Minneapolis, and the study’s principal investigator. “If the stent cannot be placed properly the patient may need additional procedures and even surgery.”
In the trial, investigators treated patients using the Diamondback 360 Orbital Atherectomy System (OAS). The catheter-based device’s crown rotates in the artery to sand the calcified portion of the plaque into minuscule particles. The device received FDA approval in October 2013.
The study, involving 443 patients at 49 U.S. sites, demonstrated that OAS aids stent delivery, with promising one-year outcomes: 94.1% of patients were free from target vessel revascularization (TVR) and target lesion revascularization (TLR). Investigators also reported lower rates of cardiac death (97% freedom from cardiac death).
The study also reviews cost differences between patients who received OAS prior to stenting and those who did not. Using a sample of patients derived from 2012 Medicare data, they compared typical treatment costs to ORBIT II patients who were pre-treated with OAS. Mean costs were $3,198 lower (P=0.003) in ORBIT II patients compared to Medicare patients.
“In addition to patient clinical outcomes, pre-treatment of these difficult-to-treat, severely calcified lesions with coronary OAS resulted in cost savings due to more efficient procedures and lower readmission rates,” said Dr. Chambers. “In an era where we are treating more patients while aiming to achieve better outcomes at greater value, these findings are significant. Not only does this procedure improve care, but it can do so more efficiently.”
Dr. Chambers receives consulting fees/honoraria from Cardiovascular Systems, Inc.
Dr. Chambers presented “Diamondback 360 Coronary Orbital Atherectomy System for Treating De Novo, Severely Calcified Lesions: ORBIT II 1-Year Results and Cost Comparison to a Sample of Medicare Hospital Claims,” on Friday, May 30, 2014, at 2:00 pm.
Real-Time Radiation Monitoring Reduces Patient and Interventional Cardiologist Exposure
RadiCure Study Evaluates Device That Beeps Upon Radiation Exposure and Reduces Treatment Variation
A real-time monitoring device that beeps in the presence of high doses of radiation can help reduce patient and interventional cardiologist exposure to radiation during cardiac catheterization, according to results of the RadiCure study, presented as a late-breaking clinical trial at the SCAI 2014 Scientific Sessions.
Advances in imaging equipment have helped reduce patient radiation exposure, but physician exposure is typically only measured months later. In the study, researchers monitored physician and patient radiation exposure using a real-time, personal radiation-monitoring device called the Bleeper Sv. The device sounds every 15 minutes in response to normal background radiation and increases its beep rate as radiation exposure increases.
For the study, 505 patients undergoing left cardiac catheterization procedures were randomized to use or not use the monitoring device. Procedure times and patient characteristics were comparable in both study groups. Following the procedure, patient and interventional cardiologist radiation exposure was measured.
Researchers found that compared to the control group, use of the monitoring device led to a significant decrease in operator exposure [0.9 (0.4-1.7) vs 1.4 (0.6-2.5) mrem, p<0.001 for the first operator and 0.5 (0.2-1.0) vs 0.7 (0.4-1.4) mrem, p<0.001 for the second operator]. Patient radiation exposure did not differ significantly between the two groups; however, there was a trend for lower Air Kerma and Dose Area Product radiation in the Bleeper Sv group [0.855 (0.58-1.507) vs 0.989 (0.610-1.802) Gray, p=0.153 and 76.68 (52.98-133.53) vs 84.61 (55.37-161.20) Gray*cm2, p=0.125, respectively].
“The device allows for immediate reaction that can limit exposure, unlike current monitoring that physicians undergo months after exposure,” said Emmanouil Brilakis, MD, PhD, FSCAI, director of the cardiac catheterization laboratories at VA North Texas Health Care System, associate professor of medicine at the University of Texas Southwestern Medical Center and the study’s principal investigator.
Georgios Christopoulos, MD, research fellow at VA North Texas Health Care System and the University of Texas Southwestern Medical Center, presented, “Effect of a Real Time Radiation Monitoring Device on Radiation Exposure During Cardiac Catheterization: the RAdiation reDuctIon during Cardiac Catheterization Using Real timE monitoring (RadiCure),” on Friday, May 30, at 2:00 pm.
Dr. Christopoulos and Dr. Brilakis report no relevant conflicts of interest.
Fractional Flow Reserve Remains Gold Standard in Determining Severity of Coronary Artery Blockages
VERIFY-2 Study Finds Two New Coronary Lesion Assessment Measures Do Not Provide Sufficient Accuracy
New measures of the severity of coronary artery blockages do not provide enough accuracy to guide treatment decisions, according to the results of the VERIFY-2 study presented as a late-breaking clinical trial at the SCAI 2014 Scientific Sessions.
Fractional flow reserve (FFR) is a well-validated technique that measures pressure differences across the blockage. FFR-guided PCI improves outcomes compared to angiography alone. However, some interventional cardiologists have been hesitant to use FFR because it requires administration of the drug adenosine, which may not be well tolerated in some patients and adds time to the procedure.
Instantaneous wave-free ratio (iFR) is a new measure that assesses the pressure difference across a stenosis during a specific period of the cardiac cycle. It is measured at rest and does not require the administration of adenosine. Another index of stenosis severity, the distal coronary pressure to aortic pressure ratio (Pd/Pa), is also measured at rest and without adenosine, but unlike iFR, it does not require any specific measurement software. The previous VERIFY and RESOLVE studies indicated that both iFR and Pd/Pa have similar levels of diagnostic accuracy (about 80%) when compared to FFR. The recent ADVISE II study demonstrated that a hybrid strategy using a combination of iFR and FFR correctly classified 94 percent of lesions compared to a strategy of using FFR in all patients, while avoiding the use of adenosine in two-thirds of the patients in the study.
“The measurement of iFR has recently been introduced to aid interventional cardiologists in their assessment of coronary lesions without the need for adenosine,” said Stuart Watkins, MD, consultant cardiologist at the Golden Jubilee National Hospital in Glasgow, Scotland. “VERIFY-2 was designed to evaluate the accuracy of this measurement compared to Pd/Pa using FFR as the currently accepted gold standard.”
In the study, researchers examined two hybrid assessment strategies: iFR-FFR with an adenosine-zone of 0.86-0.93 and Pd/Pa-FFR with an adenosine-zone of 0.87-0.94. A total of 97 patients with 120 coronary artery blockages were assessed.
They found 10.1% of lesions were misclassified using iFR-FFR, compared to 6.3% using Pd/Pa-FFR. Next, researchers compared the accuracy of iFR and Pd/Pa compared to FFR using binary cut-off values of 0.90 for iFR and 0.92 for Pd/Pa. In this analysis, the use of iFR alone would result in inappropriate PCI in 8.3% of lesions and incomplete revascularization in another 10%. Using Pd/Pa alone would result in inappropriate PCI in 4.2% of lesions and incomplete revascularization in another 10.8%.
Researchers concluded that both hybrid decision-making strategies and the use of binary cut-off values resulted in similar levels of lesion misclassification compared to FFR.
“FFR remains the gold standard — we have concluded neither iFR nor Pd/Pa is sufficiently accurate to guide decisions on the need for revascularization,” said Dr. Watkins. “Although these measures aren’t accurate enough to replace FFR, this study adds to our body of knowledge as we work to identify the most effective ways to measure lesion severity.”
Dr. Watkins reported no disclosures.
Dr. Watkins presented “Comparison of Lesion Level Decision Making in the Cath Lab Using Hyperemic and Non-hyperemic Pressure Wire Derived Indices of Stenosis Severity: The VERIFY-2 Study,” on Friday, May 30, 2014, at 2:00 pm.
New Study Supports Safety of PCI for Heart Attack in Hospitals Without Onsite Cardiac Surgery
Data from Large Quality improvement Collaborative Finds No Difference in Clinical Outcomes
An analysis of data on nearly 12,000 patients enrolled in the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (BMC2) registry has shown that heart attacks can be safely treated with percutaneous coronary intervention (PCI) in hospitals without onsite cardiac surgical back-up, without increasing the risk or death or other serious complications, according to a study reported at the SCAI 2014 Scientific Sessions.
The study addresses an important issue that has long been a subject of debate. In March 2014, SCAI, in collaboration with the American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA), released an expert consensus document with recommendations aimed at ensuring safety and quality of PCI performed in facilities without cardiac surgical back-up.
For the new study, a team led by Jason Weingart, MD, of the University of Michigan Health System in Ann Arbor, analyzed data on 11,920 patients treated with PCI for ST-elevation myocardial infarction (STEMI). Of these patients, 9,547 were treated at hospitals with onsite cardiac surgery and 2,373 were treated at hospitals without. Overall, there was no significant difference between the two groups in the rates of serious procedure-related complications, such as stroke, heart failure, the need for kidney dialysis, complications at the arterial puncture site, excessive bleeding or need for coronary artery bypass grafting. The researchers had access to extra data for 2,243 Medicare patients and found no significant difference in the risk of in-hospital or long-term death rates or the need to be readmitted to the hospital within 30 days. The researchers did note that patients treated at hospitals without onsite cardiac surgery were significantly more likely to be transferred to other acute care hospitals upon discharge and significantly less likely to be referred for cardiac rehabilitation.
Dr. Weingart reports no potential conflicts of interest.
Dr. Weingart presented the study “Outcome of Primary PCI with and without Cardiac Surgical Backup in Michigan: Insights from the BMC2 registry” in a poster session on May 28, 2014, from 1:00-4:00 pm.