Coronary artery remodelling

From atherosclerotic coronary ectasia to aneurysm: a case report and literature review

In contrast to Kawasaki syndrome the formation of coronary aneurysms caused by atherosclerosis has hardly been demonstrated. We report on a 56-year old patient, admitted to our hospital for cardiovascular evaluation before carotid surgery. He had no anginal pain, but a history of coronary artery disease with previous anterior myocardial infarction. Angiography revealed a collateralized LAD occlusion. Myocardial scintigraphy only demonstrated fixed perfusion defects. Surprisingly, MR imaging revealed large coronary aneurysms of the RCX and RCA. Angiographic follow up showed a rapid progression of ectatic towards aneurysmatic coronary lesions within 3 years. General pathophysiological mechanisms promoting ectatic coronary artery disease as a structural failure of the atherosclerotic remodelling process itself and chronic dilatatory stimuli due to endogenous and exogenous factors are discussed.

Relation between coronary artery remodelling (compensatory dilatation) and stenosis in human native coronary arteries

OBJECTIVES

To investigate the contribution of plaque size and vessel remodelling to coronary artery stenosis and to assess the role of vessel shrinkage (negative remodelling) across a wide range of lesions.

DESIGN

Postmortem study of coronary remodelling in perfusion fixed hearts.

SUBJECTS

24 men and 24 women who died suddenly with coronary artery disease.

MAIN OUTCOME MEASURES

Percentage stenosis, percentage plaque burden, percentage remodelling, and arc of normal vessel were measured and related to age, sex, smoking status, and history of hypertension.

RESULTS

There was a positive relation between percentage stenosis and percentage plaque burden (r = 0.6, p < 0.0001) and an inverse relation between percentage stenosis and percentage remodelling (r = -0.4, p < 0.0001). Multilinear regression modelling showed that luminal stenosis = 1.0 (plaque burden) - 0.4 (vessel remodelling). Remodelling was greater in lesions that would not have been significant at angiography (</= 25% stenosis) than in the remaining lesions (25.9 (26)% v 10.0 (21.1)%, p < 0.0001, respectively) and was reduced in segments with circumferential plaques (12.7 (24.5)% v 20.7 (24.3)% in eccentric plaques, p = 0.001). Remodelling did not correlate with age, sex, or smoking. Negative remodelling was present in 62 lesions with a stenosis > 25% versus 10 lesions with </= 25% stenosis (p < 0.0001). Lesions with negative remodelling had greater plaque burden and luminal stenosis and a reduced arc of normal segment.

CONCLUSION

Outward arterial remodelling negates the stenosing effect of increasing plaque size. Significant coronary stenoses arise from a failure of this outward remodelling in the face of a large plaque burden. Coronary arterial remodelling is unrelated to sex or smoking and is plaque specific.

Relation between coronary artery remodelling (compensatory dilatation) and stenosis in human native coronary arteries

OBJECTIVES

To investigate the contribution of plaque size and vessel remodelling to coronary artery stenosis and to assess the role of vessel shrinkage (negative remodelling) across a wide range of lesions.

DESIGN

Postmortem study of coronary remodelling in perfusion fixed hearts.

SUBJECTS

24 men and 24 women who died suddenly with coronary artery disease.

MAIN OUTCOME MEASURES

Percentage stenosis, percentage plaque burden, percentage remodelling, and arc of normal vessel were measured and related to age, sex, smoking status, and history of hypertension.

RESULTS

There was a positive relation between percentage stenosis and percentage plaque burden (r = 0.6, p < 0.0001) and an inverse relation between percentage stenosis and percentage remodelling (r = –0.4, p < 0.0001). Multilinear regression modelling showed that luminal stenosis = 1.0 (plaque burden) − 0.4 (vessel remodelling). Remodelling was greater in lesions that would not have been significant at angiography (⩽ 25% stenosis) than in the remaining lesions (25.9 (26)% v10.0 (21.1)%, p < 0.0001, respectively) and was reduced in segments with circumferential plaques (12.7 (24.5)% v20.7 (24.3)% in eccentric plaques, p = 0.001). Remodelling did not correlate with age, sex, or smoking. Negative remodelling was present in 62 lesions with a stenosis > 25% versus 10 lesions with ⩽ 25% stenosis (p < 0.0001). Lesions with negative remodelling had greater plaque burden and luminal stenosis and a reduced arc of normal segment.

CONCLUSION

Outward arterial remodelling negates the stenosing effect of increasing plaque size. Significant coronary stenoses arise from a failure of this outward remodelling in the face of a large plaque burden. Coronary arterial remodelling is unrelated to sex or smoking and is plaque specific.

Size of emptied plaque cavity following spontaneous rupture is related to coronary dimensions, not to the degree of lumen narrowing. A study with intravascular ultrasound in vivo

OBJECTIVE

To identify any potential relations between the size of an emptied plaque cavity and the remodelling pattern, plaque or vessel dimensions, lumen narrowing, and other ultrasonic lesion characteristics.

DESIGN

Intravascular ultrasound was used to examine prospectively 51 ruptured ulcerated coronary plaques. Cross sectional area measurements comprised lumen, vessel, plaque, and emptied plaque cavity. Lumen narrowing was calculated as 1 - (lesion lumen area/reference lumen area) x 100%. A remodelling index was calculated as lesion vessel area/reference vessel area, and plaques were divided into those with values > 1.05 (group A) and </= 1.05 (group B).

RESULTS

Of the total of 51 plaques, 36 (71%) were assigned to group A and 15 (29%) to group B. In neither group was there a significant difference in reference dimensions and lumen narrowing. However, lesion vessel (mean (SD): 22.6 (8.1) mm(2) v 17. 5 (4.3) mm(2); p = 0.006) and plaque areas (15.8 (6.2) mm(2) v 12.8 (3.2) mm(2); p = 0.03) were greater in group A than in group B. The cavity inside the plaque was larger in group A than in group B (2.8 (1.6) mm(2) v 1.8 (0.9) mm(2); p = 0.007) and showed a positive linear relation with lesion and reference vessel size (r = 0.58 and 0.56, respectively; p < 0.001), but not with lumen narrowing.

CONCLUSIONS

The size of the emptied cavity inside ruptured plaques is on average larger in lesions with adaptive vascular remodelling, and shows a linear relation with lesion plaque and vessel size and with the reference dimensions, but not with the degree of lumen narrowing.

Preintervention lesion remodelling affects operative mechanisms of balloon optimised directional coronary atherectomy procedures: a volumetric study with three dimensional intravascular ultrasound

AIMS

To classify atherosclerotic coronary lesions on the basis of adequate or inadequate compensatory vascular enlargement, and to examine changes in lumen, plaque, and vessel volumes during balloon optimised directional coronary atherectomy procedures in relation to the state of adaptive remodelling before the intervention.

DESIGN

29 lesion segments in 29 patients were examined with intravascular ultrasound before and after successful balloon optimised directional coronary atherectomy procedures, and a validated volumetric intravascular ultrasound analysis was performed off-line to assess the atherosclerotic lesion remodelling and changes in plaque and vessel volumes that occurred during the intervention. Based on the intravascular ultrasound data, lesions were classified according to whether there was inadequate (group I) or adequate (group II) compensatory enlargement.

RESULTS

There was no significant difference in patient and lesion characteristics between groups I and II (n = 10 and 19), including lesion length and details of the intervention. Quantitative coronary angiographic data were similar for both groups. However, plaque and vessel volumes were significantly smaller in group I than in II. In group I, 9 (4)% (mean (SD)) of the plaque volume was ablated, while in group II 16 (11)% was ablated (p = 0.01). This difference was reflected in a lower lumen volume gain in group I than in group II (46 (18) mm(3) v 80 (49) mm(3) (p < 0.02)).

CONCLUSIONS

Preintervention lesion remodelling has an impact on the operative mechanisms of balloon optimised directional coronary atherectomy procedures. Plaque ablation was found to be particularly low in lesions with inadequate compensatory vascular enlargement.

Mechanisms of progression in native coronary artery disease: role of healed plaque disruption

OBJECTIVE

To determine the role of healed plaque disruption in the generation of chronic high grade coronary stenosis.

METHODS

Coronary arteries obtained at necropsy were perfuse fixed with formal saline for 24 hours at 100 mg Hg. The percentage lumen diameter stenosis was measured in each 3 mm segment containing a plaque, using the lumen size at the nearest histologically normal segment as the reference point. Each segment was prepared for histological examination and stained with Sirius red and immunohistochemistry for smooth muscle actin. Healed disruption was considered to be present when under polarised light there was a break in the yellow-white dense collagen of the cap filled in by more loosely arranged green collagen. Increased smooth muscle density in the green staining areas was required. Each section was read independently by two observers; any segment with discordant views was considered negative.

MATERIAL

31 men aged 51-69 dying suddenly of ischaemic heart disease. 39 coronary arteries were studied containing 256 separate plaques, after excluding coronary arteries with old total occlusions, an acute culprit thrombotic lesion, diffuse disease without normal arterial segments, and arteries related to old myocardial scars.

RESULTS

16 of 99 plaques causing < 20% diameter stenosis had prior disruption. In the 21-50% stenosis range 16 of 86 plaques showed healed disruption. Stenosis >/= 51% by diameter was present in 71 plaques, 52 of which showed a healed disruption pattern. The difference between stenosis < 50% and stenosis >/= 51% was significant by the chi(2) test (p < 0.001).

CONCLUSIONS

Subclinical episodes of plaque disruption followed by healing are a stimulus to plaque growth that occurs suddenly and is a major factor in causing chronic high grade coronary stenosis. This mechanism would explain the phasic rather than linear progression of coronary disease observed in angiograms carried out annually in patients with chronic ischaemic heart disease.

Coronary artery remodelling and the assessment of stenosis by pathologists

When atherosclerotic plaques develop, the cross-sectional area of the artery at that point often increases to accommodate the plaque without any reduction in lumen size. In consequence the angiogram does not detect a high proportion of atherosclerotic plaques. The increase in size of the artery (compensatory dilatation-arterial remodelling) varies widely in degree between different plaques even in the same artery. Dilatation of a degree to prevent any loss of lumen size is regarded as adequate compensatory dilatation. In contrast, other plaques are associated with no or minimal increase in the vessel cross-sectional area and a reduction in lumen size in present (inadequate compensation). High-grade stenosis is in particular associated with a total failure of remodelling. Such plaques may have had a rapid growth phase, out-pacing the ability of the medial smooth muscle cells to undergo a rearrangement. The phenomenon of remodelling has important consequences for pathologists who use the traditional method of comparing the lumen size relative to the cross-sectional area of the vessel at the site of a plaque to measure stenosis. The area of the vessel at this point may be anything up to 60% above its size before the plaque developed. An error is introduced which on average overestimates diameter stenosis by 30% when compared to an angiographic equivalent method in which the lumen size at the lesion is compared to the lumen size at an adjacent segment of artery without a plaque.