Download Clinical Angiography

Clinical Angiography
Case Study
USE OF FRACTIONAL FLOW RESERVE (FFR) TO AID
DIAGNOSIS IN BORDERLINE CORONARY ARTERY
STENOSIS
By Nishantha Navaratne
CLINICAL HISTORY
A 53 year old female was referred to the cardiology clinic by her GP. She was experiencing
intermittent chest pain and shortness of breath during exercise with both typical and atypical
features of acute coronary syndrome. She had a number of risk factors of coronary artery disease,
including smoking, diabetes, hypertension and raised serum creatinine of 120 µmol/L (normal
value between 40-90µmol/L for female). She had no previous cardiac history and no known family
history of coronary artery disease. She had been experiencing symptoms for a few weeks and
underwent treadmill stress ECG at clinic. Her resting ECG was normal, but she managed only 3
minutes on the treadmill test which was 90% of her target. She was fatigued and breathless after
the treadmill test with some sharp chest pain; however, her echocardiogram showed normal left
ventricular function. She was referred for coronary angiogram on 28/09/2010 for further
investigations with suspected coronary artery disease.
CORONARY ANGIOGRAM
The procedure was explained to the patient and the risks (stroke, bruising, heart attack,
haematoma etc.) and benefits (diagnosis and treatment) were discussed allowing informed
consent. Routine checks such as name, date of birth, allergies, asthma, diabetes, current
medications, LMP (10 day rule) and pregnancy were checked in line with IR(ME)R regulations.
Coronary catheterization was performed in the catheter lab under aseptic technique using a
Philips Allura Xper U–arm with the patient supine on the X-ray table. She had been fasted for 4
hours, and mild sedation was given to help her to relax. The local anaesthesia was applied to her
right wrist over the radial artery. The right radial artery was punctured with a needle using
seldinger technique, and a wire was passed through the needle into the radial artery. Then the 6F
1
introducer radial sheath advanced over the wire and placed within the vessel. The right coronary
angiogram was done first using a 5F 4.0 right coronary catheter and the left coronary angiogram
with a 6F 3.5 left catheter. A minimum number of cine acquisitions were taken and a low
fluoroscopic mode used in 15 fr/s and FOV 25cm used throughout the procedure. Visipaque 320
(Iodixanol 320 mgI/ml) totalling 60mls were injected into coronary arteries by hand. Collimation
and filters were applied to reduce the radiation dose to both the patient and staff.
The coronary angiogram (Figure 1) showed a bifurcation lesion (50% - 70 %) in the proximal left
anterior descending (LAD) artery involving a diagonal branch. The rest of the coronary arteries
appeared normal. Although the lesion was visually significant, it was not compatible with her
previous clinical findings. Therefore, another diagnostic test needed to measure the severity of the
lesion prior to any clinical decision making.
Figure 1 PA cranial 30º
Figure 2 PA cranial 30º
LAD- left anterior descending artery
FFR wire in diagonal branch
Figure 3 PA cranial 30º
FFR wire in LAD
A coronary angiogram provides an image of the patent vessel only (Fearon et al, 2002). In recent
years, fractional flow reserve (FFR) is used as a diagnostic tool to evaluate blood flow across a
2
particular lesion to avoid the limitations of an angiogram. The FFR measures the physiological
impact of lesion severity and provides an accurate anatomical assessment of the lesion (Aude Y,
& Luis G.2003). Given the angiographic findings in this situation, it was decided that FFR would
aid in this patient’s clinical management.
FRACTIONAL FLOW RESERVE (FFR)
FFR is maximum achievable blood flow to the myocardium supplied by a stenotic artery as a
fraction of normal maximum flow pressure distal to the lesion divided by the pressure at the tip of
the catheter. Thus, in the absence of any coronary lesion, a normal value is 1.0, as these two
pressures would be equal. However, a FFR value of < 0.75 identifies a stenosis associated with
inducible ischemia. FFR value of > 0.75 means the blockage is not severe enough to limit blood
flow to the myocardium (Hau, WK, 2004).
FFR PROCEDURE
FFR was performed using a 0.014 inch pressure sensor mounted guide wire which is connected to
the analyzer. This wire was introduced through a 6F Voda 3.5 guide catheter, and then calibrated
at the aortic root. Then advanced into the LAD (Figure 3) and positioned about 2cm distal to the
lesion. An intravenous infusion of Adenosine (Vasodilator) was administered at the rate of
100
to induce maximum hyperaemia while the guide wire is pulled back through the lesion.
The analyzer collects and interprets signals from the guide wire to be simultaneously displayed on
both analyzer and the catheter lab hemodynamic screen. Then the procedure was repeated in the
diagonal branch (Figure2). The analyzer showed the FFR value in the LAD as 0.92 and 0.93 in
diagonal branch which was well above the minimum value of 0.75. These measurements proved
that both lesions were not significant enough for an intervention and can be managed by
medically.
PROCEDURAL CONCLUSION
The severity of the coronary lesions under assessment in this study was not clear enough with
angiography alone to reach the correct clinical decision. The use of FFR provided measurements
that proved both LAD and diagonal lesions were not significant enough for further intervention.
This prevented unnecessary stents with their complications, unnecessary radiation, contrast
related complications and the consequential necessity of dual anti platelet therapy and cost.
CRITICAL EVALUATION OF ASPECT OF THE TECHNIQUE
Critical evaluation of the importance of FFR as an aid to angiography will now be discussed. How
FFR was able to assist in an accurate diagnosis leading to appropriate patient management will
also be discussed.
Fearon et al (2002) explained FFR is considered as an accurate diagnostic method for
determining the physiological significance of borderline coronary lesions and distinguishes flow
limiting lesions from those that are not. It has been proven that in patients with FFR of >0.75,
deferral of Percutaneous coronary intervention (PCI) is safe and results in excellent clinical
outcomes (Tio et al, 2005). As coronary angiogram provides 2 dimensional images, it is not always
possible to justify the lesion as significant (Higano et al, 2001). Often, operators are mislead by the
3
angiographic appearances as they do not represent the reality of the stenosis. If a non significant
lesion is identified as significant depending on the angiographic images alone, it would result in
unnecessary PCI (Hau, WK. 2004).
A study done by Verna et al (2006), reported that performing FFR prevented 50% of stents being
required as they were deemed unnecessary. Their study further demonstrated that the risk of
adverse cardiac events and revascularization in patients with FFR>0.75 who did not have PCI was
lower than the risks associated with PCI. In their study on 112 patients with 175 stenosis including
71 multi-vessel CAD patients (63%) and 30 patients (27%) with unstable symptoms. Based on the
results of FFR, PCI was deferred for 67 stenosis in 54 patients (FFR>0.75, group I). In the
remaining 58 patients (group II) with 108 diseased vessels, PCI was performed in one or more
functionally significant stenosis (FFR <0.75) and deferred in non significant stenosis (FFR >0.75).
After 34 months follow up, MACE (major adverse cardiac events) occurred in 12.9% of group I
patients and in 24.1% of group II patients, TVR (target vessel revascularization) was required in
5% of the stenosis untreated based on FFR result in both groups and in 12.6% of stenosis that
underwent PCI.
Assessment of severity of coronary bifurcation lesion remains one of the most challenging
subjects in PCI. Treatment of these lesions is associated with low procedural success and high
complication and restenosis rates (Williams et al, 2001). Angiographic assessment of the
bifurcation lesion is often obscured by overlap of adjacent vessels, angulations, foreshortening or
origin of the side branch (Koo et al, 2005). Their study too, proved that the use of FFR to assess
bifurcation lesions can prevent unnecessary PCI.
As this particular patient underwent FFR study, a possible unnecessary PCI was avoided. As a
result, the following potential complications were prevented. As discussed, the restenosis rate
after stenting would have been very much higher than if it was not a bifurcating lesion. Brilakis
and Berger (2008) indicated that PCI of bifurcation lesions are associated with an unusually high
risk of complications. As this is a diabetic patient, the re-stenotic rate would have been higher than
the non diabetic patients. Kip et al (1996) found that 9 year mortality rate due to restenosis was
twice as high in diabetic patients treated with PCI. Further, Blankenbaker et al (1998)
demonstrated that the restenosis rate was up to 40% after stenting for diabetic patients compared
with 20% of non diabetic patients. Another disadvantage of carrying out intervention for a diabetic
patient is incomplete revascularization (Hammoud et al, 2000). As the lesion was identified as non
significant, PCI was not performed and such potential unnecessary revascularization was avoided.
Stent thrombosis occurs in <1% of cases resulting in myocardial infarction, urgent target lesion
revascularization (TLR) and death. A study done by Mintz et al (1998) revealed that restenosis
rates range from 10% to 58% following PCI.
Post interventional medication includes duel antiplatelet therapy (Aspirin & Clopidogrel) which can
cause uncontrolled bleeding. For this reason the patient’s life might be at risk and the patient may
not be suitable for other surgical procedures due to risk of bleeding. Some antiplatelet agents can
also cause peptic ulcers and the other side effects (Wenaweser et al, 2005). Some patients
neglect or forget their daily medication that may result in possible restenosis of the stent.
Therefore, the patient’s lifestyle is directly affected by the choice of whether to perform coronary
intervention PCI.
4
Renal function is directly related to mortality in patients with CAD undergoing PCI (Sadeghi et al,
2003). Many studies have found diabetes mellitus as an independent risk factor for contrast
induced nephropathy (CIN) for patients undergoing coronary PCI (Rihal et al, 2002). Usage of
higher volume of contrast is largely associated with CIN. McCullough et al (1997) showed that the
risk of CIN is minimal in patients receiving less than 100mls of contrast media. In this case, if
these non flow limiting bifurcation lesions were mistakenly diagnosed as flow limiting, a large
amount of contrast would be required for PCI. As this patient was diabetic and had raised
ceatinine clearance (poor kidney function) an unnecessary PCI may have lead to CIN and acute
renal failure.
A study done by Boetticher et al (2003) reported how patients are exposed to a high dose of
ionizing radiation due to long procedural time and high frame rates (15f/s) during coronary
intervention. Therefore, unnecessary PCI should be avoided whenever necessary using
techniques such as FFR to fully evaluate lesions.
Stents and other related consumables used in interventional procedures are very expensive.
Therefore, it is advisable that an intervention should only be done after appropriate evaluation of
the lesion concerned. FFR technique has proved that it is a very important tool to measure border
line lesions before proceeding for high cost interventional procedure. Dick et al (1991) indicated
that the stenting may increase the in hospital cost by about 50% and unnecessary stenting may
increase this figure up to 100%.Further hospital resources could be wasted unnecessarily if
proceeding for intervention is not justified.
EVALUATION CONCLUSION
The severity of the lesion under assessment in this study was not suitably clear with angiography
alone to reach the correct clinical decision. As, is widely accepted the appearance of angiographic
images can be subjective leading to the severity of lesions can be incorrectly judged. Although
coronary stenting is the accepted technique for flow limiting lesions, in this case it was appropriate
to use FFR for further diagnosis of the lesion to avoid stent related complications, unnecessary
costs and lifestyle changes. FFR in this the case has given a definitive diagnosis that the lesion is
not flow limiting. FFR is a simple, cost effective and reliable method to assess the severity of a
borderline lesion. Therefore, medical management to control the coronary artery disease
combined with minimizing associated risk factors was the best course of treatment in this case.
REFERENCES
01 Aude, Y. Luis, G. (2003). How to prevent unnecessary coronary interventions: identifying
lesions responsible for ischemia in the cath lab. Current Opinion in Cardiology. 18 (5), 394-399.
02 Blankenbaker R, Ghazzal Z, Shen Y, Ghazzal Z, King SB (1998). Clinical outcome of diabetic
patients after stent implantation. Journal of American College of Cardiology.31, 415-418.
03 Boetticher H, Meenen C, Lachmund J, Holfmann W, Engel HJ (2003). Radiation exposure to
personnel in cardiac catheterization laboratories. Z Medical Physics. 13(3), 251-256.
5
04 Brilakis ES & Berger PB (2008). Treatment of coronary bifurcations: might less be more?
European Heart Journal.29:704-706. Downloaded from eurheartj.oxfordjournals.org. (Accessed 1
November, 2010)
05 Dick RJ, Popma JJ, Muller DW, Burek KA, Topol EJ (1991). In-hospital costs associated with
new percutaneous coronary devices. American Journal of Cardiology. 68: 879-85.
06 Fearon WF, Pijls NH, Klauss V, Powers E, Takazawa K (2002). Coronary pressure
measurement after stenting predicts adverse events at follow-up: a multicentre registry. Circulation
.105: 2950-2954.
07 Hammoud T, Tanguay J, Martial G, Bourassa (2000). Management of Coronary Artery
Disease: Therapeutic Options in Patients with Diabetes. Journal of the American College of
Cardiology. 36(2), 355-366. Downloaded from
http://content.onlinejacc.org/cgi/content/full/36/2/355. (Accessed 3 November, 2010)
08 Hau, WK. (2004). Fractional flow reserve and complex coronary pathologic conditions.
European Heart Journal. 25 (3), 723-727. Downloaded from eurheartj.oxfordjournals.org on
November 5, 2010.
09 Higano ST, Segno, DI. Rihal, CS (2001). Incremental doses of intracoronary adenosine for the
assessment of coronary velocity reserve for clinical decision making. Catheter Cardiovascular
Intervention.54 (15):34-40.
10 Kip KE, Faxon DP, Detre KM, Yeh W, Kelsey SF (1996). Coronary angioplasty in diabetic
patients. Circulation. 94:1818-1825.
11 Koo BK, Kang HJ, Youn TJ, Chae IH, Choi DJ, Kim HS (2005). Physiologic assessment of
jailed side brach lesions using fractional flow reserve. J Am Coll Cardiol. 46: 633-637.
12 McCullough PA, Wolyn R, Rocher LL, Levin RN, O’Neill W (1997). Acute renal failure after
coronary intervention. American Journal of Medicines. 103(5), 368-375.
13 Mintz GS, Hoffmann R, Mehran R (1998). In-stent restenosis: the Washington Hospital Centre
experience. American Journal of Cardiology: 817E-13E.
14 Rihal CS, Textor SC, Grill DE (2002). Incidence and prognostic importance of acute renal
failure after percutaneous coronary intervention. Circulation.105 (19), 2259-2002.
15 Sadeghi HM, Stone GW, Grines CL (2003). Impact of renal insufficiency in patients undergoing
angioplasty for acute myocardial infarction. Circulation. 108(22), 2769-2775.
16 Tio RA, Wijpkema JS, Vander Vleuten PA, Jessurun GA (2005). Long-term safety of
intracoronary haemodynamic assessment for deferral of angioplasty in intermediate coronary
stenosis: a 5 year follows up. Acta Cardiol. 60:207-211.
17 Verna E, Lattanzio M, Ghiringhelli S, Provasoli S, Caico SI (2006). Performing versus deferring
coronary angioplasty based on functional evaluation of vessel stenosis by pressure
measurements: s clinical outcome study. Journal of Cardiovascular Med.7:169-175.
6
18 Wenaweser P, Dorffler-Melly J, Imboden K, Windecker S, Togni M, Meier B, Haeberli A, Hess
OM. (2005). Stent thrombosis is associated with an impaired response to antiplatelet therapy.
Journal of American College of Cardiology. 45, 1747-1752.
19 Williams DO, Suwaidi J, Cohen HA, Detre KM, Holmes DR (2001). Immediate and one yeat
outcome in patients with coronary bifurcation lesions in the modern era. Am J Cardiol .87:11391144.
7