BSCI Case of the Month December 2008
Positive re-modelling: an iceberg waiting for the Titanic
SH Barr and JA Purvis
Dept of Cardiology, Western HSC Trust, Londonderry,
Northern Ireland
A 57 yr old male attended rapid access chest pain clinic with a 1 month history of chest discomfort on exertion. Risk factors included positive family history of IHD, ex-smoker, hypertension and impaired glucose tolerance.
He managed 7 minutes of a Bruce protocol test achieving satisfactory heart rate. He had no chest pain but developed 1mm of ST segment depression in the lateral chest leads. Duke treadmill score suggested intermediate risk so he was referred for CT coronary angiogram.
This was performed on the Philips Brilliance 64 CT scanner in Tyrone County Hospital, Omagh. The patient was on a beta-blocker plus anti-hypertensive drugs prior to procedure but despite this and 10mg of intravenous metoprolol, his heart rate remained elevated at 68 bpm so a standard protocol was used rather than step and shoot. He was given 400 mcg of glyceryl trinitrate just prior to the contrast study.
Agatston score was 12 on calcium scan, with minimal calcific plaque in the LAD and RCA. Contrast study revealed a severe stenosis in segment 2 of right coronary artery, which was felt to be the cause of his symptoms. A large, lipid-rich plaque was identified in close relationship to distal left main stem and proximal left anterior descending coronary artery. The plaque exhibited positive re-modelling with no significant luminal intrusion but contrast could be identified within, suggesting plaque ulceration (Figure 1, Video 1).
Video 1 Needs Flash Player plug-in to view
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Figure 1: CT Images 3D-ball view of Aorta in centre with Left Main Stem (LMS) coronary artery at 4pm and Right coronary artery (RCA) at 9pm.There is a tight stenosis in the RCA and a large soft plaque with haemorrhage in the distal LMS and proximal Left Anterior Descending (LAD). |
Figure 2: Cardiac Catheterisation This view shows LMS, LAD and Left circumflex (LCx) vessels. There is some irregularity of the vessels but no significant intrusive plaque is seen, The arrow points to extravasation of contrast into the positively remodelled plaque with haemorrhage clearly seen in Fig 1. |
Figure 3: Cardiac Catheterisation RCA has severe stenotic plaque just after a small branch as in Fig 1. |
The invasive cardiology team
initially felt that they couldn’t see any disease on the left
corresponding to the CT findings until plaque haemorrhage visible in the
CT was also demonstrated in the catheter angiogram (Figure 2, arrow).
Percutaneous coronary intervention was organised for the RCA lesion but
much debate occurred about management options for the left sided plaque.
Lipid rich plaque with little calcification is
commoner in the diabetic and pre-diabetic population [1] Stenting is not
recommended for non-intrusive lesions unless objective evidence of
stress related ischaemia can be demonstrated [2], and putting a
by-pass graft into a widely patent artery can lead to competitive flow
with rapid occlusion of the graft. It was felt that IVUS or pressure
wire assessment would confirm findings but not further management in
this case.
The patient has been commenced on an aggressive preventative regimen of top dose statin, aspirin, clopidogrel, beta-blocker and ACE inhibitor. A fibrate has been added in to improve protective HDL cholesterol levels. The aim of medical treatment will be to induce plaque stabilisation or possibly regression but overall the patient will need careful surveillance of a vulnerable plaque located in a potentially lethal site [3].
Any comments about the images in this case or suggestions on management of positive remodelling are welcomed by the authors and should be posted to the BSCI member’s forum.
References
1. Scholte A, Schuijf J, Kharagjitsingh A et al. Prevalence of coronary artery disease and plaque morphology assessed by multi-slice computed tomography coronary angiography and calcium scoring in asymptomatic patients with type 2 diabetes. Heart 2008;94;290-295
2. Silber S, Albertsson P, Fernandez-Aviles F et al. Guidelines for percutaneous coronary interventions. EHJ 2005;26:804-847.
3. Hamm C, Heeschen C, Falk E, Fox K. Acute coronary syndromes: pathophysiology, diagnosis and risk stratification. In: Camm A, Luscher T and Serruys P (eds). The ESC Textbook of cardiovascular medicine, 1st edition, 2006. Oxford: Blackwell Publishing Ltd, pp338 – 345.