Post-procedural quantitative flow ratio gradient and target lesion revascularization after drug-coated balloon or plain-old balloon angioplasty

Background

Balloon angioplasty, including drug-coated balloon (DCB), is an important option of percutaneous coronary interventions (PCI), even in the drug-eluting stent era. Although quantitative coronary angiography (QCA) has been frequently used to determine the optimal endpoint of balloon angioplasty, physiological assessment may add incremental prognostic values. Quantitative flow ratio (QFR) has evolved as a novel 3D QCA-based physiological index to estimate fractional flow reserve without hyperemia nor pressure guidewire, offering both anatomical and functional lesion assessments. This study aimed to characterize post-procedural anatomical and physiological indexes by QFR and to compare their prognostic impacts on long-term clinical outcomes.

Methods

This retrospective study included 98 patients with de novo (n=39) or in-stent restenosis (n=59) lesions who underwent PCI with DCB (n=69) or plain-old balloon angioplasty (POBA, n=29). All lesions were analyzed by QCA and QFR. QCA analysis measured lesion length, reference lumen diameter (RLD), minimum lumen diameter (MLD) and percent diameter stenosis (%DS) at pre- and post-procedures as anatomical indexes. QFR analysis measured post-procedural QFR of target vessel (QFR-vessel) and QFR-gradient (ΔQFR between proximal and distal segments of the lesion) as physiological indexes. Primary endpoint was target lesion revascularization (TLR) within 1-year post-procedure.

Results

Target lesion profiles were as follows: lesion length 26.3±16.6 mm, RLD 2.90±0.70 mm, MLD 0.94±0.32 mm and %DS 79.3±18.6%. At post-procedure, MLD, residual %DS, QFR-vessel and QFR-gradient of target lesions were 1.88±0.49 mm, 34.7±10.6%, 0.84±0.13 and 0.06±0.04, respectively. During 1 year post-procedure, TLR occurred in 19 (19%) patients. Patients with TLR showed smaller MLD (1.66±0.45 mm vs. 1.93±0.49 mm, p=0.028) and QFR-vessel (0.79±0.03 vs. 0.85±0.01, p=0.06), and greater residual %DS (42.7±11.3% vs. 32.8±9.5%, p=0.0002) and QFR-gradient (0.12±0.06 vs. 0.04±0.02, p<0.0001) at post-procedure compared with those without. In multivariate analysis including several clinical characteristics and anatomical indexes, QFR-gradient at post-procedure was independently associated with TLR within 1-year, demonstrating higher prognostic value compared with post-procedural MLD and residual %DS (Figure). The receiver-operating characteristics curve analysis identified the best cut-off value of QFR-gradient as 0.08 for predicting 1-year TLR after balloon angioplasty, irrespective of balloon type (DCB or POBA) (Figure 1).

Conclusions

Post-procedural QFR-gradient within the lesion was an independent and stronger predictor of subsequent TLR, compared with anatomical indexes. Further studies are warranted to investigate whether QFR guidance to optimize PCI procedure could improve clinical outcomes in patients with balloon angioplasty.

Figure 1

Funding Acknowledgement

Type of funding source: None

[Late coronary artery aneurysm formation following directional coronary atherectomy]

The most important factor to reduce late restenosis following directional coronary atherectomy is the technical provision of the largest luminal diameter as possible. However, the safety of deep arterial resection and the resulting arterial perforation or late aneurysm formation is questionable. This study examined the frequency of coronary artery aneurysm formation in patients treated by directional coronary atherectomy. Ninety-eight patients with 123 lesions were analyzed by quantitative angiographic and histologic data. Coronary aneurysms (ratio of dilated vessel segment to the adjacent reference segment > 1.2:1) occurred in seven patients (seven lesions: 5.7%). Specimens were categorized by the deepest layer retrieved. Forty lesions (32.5%) were treated by resection of the intima alone, 65 (52.8%) by resection of the medial tissues and 18 (14.6%) received resections of the adventitial tissues including fatty tissues in three lesions. Late coronary aneurysms occurred often in lesions with resection of adventitial tissue (38.9%) and occurred in all three lesions with resections of fatty tissues. Six coronary aneurysms occurred in the left anterior descending artery (six in segs. 6, 7), and one aneurysm in the left circumflex artery. Among the target lesions in which coronary artery aneurysms were formed, six lesions were primary lesions and one lesion was a restenotic lesion after percutaneous transluminal coronary angioplasty. Statistically, patients with coronary artery aneurysms frequently have associated hypertension (p = 0.02) but rarely diabetes mellitus (p = 0.05). Lesions with late aneurysms had significantly high specimen weight (p = 0.01) and a trend to lower postprocedure % diameter (p = 0.20). There was no significant preprocedural angiographic predictor of aneurysms such as minimal lumen diameter or reference vessel diameter.

[Characteristics of 201Tl myocardial SPECT and left ventriculography in patients with acute diagonal branch myocardial infarction]

Characteristics of 201Tl myocardial SPECT and ventriculography were studied in 13 patients with acute diagonal branch myocardial infarction. Rest 201Tl myocardial SPECT and left ventriculography were underwent in chronic phase. In 5 patients ECG changes in acute phase were not definite. In 6 patients it was difficult to identify the obstructed coronary artery with coronary angiography in acute phase. Mean value of maximum CPK was 854 (458-1,774) U/l. It seemed to be difficult to diagnose acute diagonal branch myocardial infarction with ECG and/or coronary angiography. In all patients defects were noted on 201Tl SPECT. Defects were small and noted in the central anterior wall and not in the septum. In 2 patients defects were noted at apex. In left ventriculography dyskinetic motion was noted in 10 patients; one patient showed apical aneurysm and 3 patients showed anterior wall aneurysm. In 3 patients anterior wall showed akinesis. It was concluded that 201Tl myocardial SPECT were useful for detecting diagonal branch lesion. In case of diagonal branch myocardial infarction size of defects were small and defects were not noted in the septum, however aneurysmal motion was frequently noted.

Incidence of acetylcholine-induced spasm of coronary arteries subjected to balloon angioplasty

To examine the vasospastic activity of coronary arteries which have been subjected to previous balloon angioplasty, we conducted an acetylcholine provocative test at diagnostic catheterization in 147 consecutive patients. All patients underwent successful elective angioplasty and had follow-up angiography 1 to 6 months after the procedure. Sixty-two patients had a history of prior myocardial infarction and 43 patients had multivessel coronary artery disease. Angioplasty was performed on 176 vessels. Incremental doses of acetylcholine (25 micrograms, 50 micrograms, 100 micrograms) were injected into the right and left coronary arteries over a period of 1 min. The incidence of coronary spasm of arteries which had been subjected to angioplasty was 44%. Angiographic restenosis was observed in 59 patients (40%). There was no correlation between the occurrence of coronary spasm and the presence of restenosis. The maximal dose of injected acetylcholine was smaller in patients with positive evidence of spasm than in patients with negative evidence of spasm (55 +/- 27 micrograms vs 82 +/- 28 micrograms, p < 0.01). In patients with single vessel coronary artery disease, the incidence of spasm of the contralateral artery, i.e. the artery without angioplasty, was lower than that of the artery subjected to angioplasty (22% vs 46%, p < 0.01). Thus, the data suggest that coronary arteries which have been previously subjected to angioplasty have enhanced vasospastic activity in response to acetylcholine.

[Scintigraphic appearance in stress 201Tl myocardial SPECT of midportion lesion in left anterior descending artery]

Scintigraphic appearance of left anterior descending artery (LAD) lesion in stress 201Tl myocardial SPECT was studied in 43 patients (pts) with midportion lesion in LAD confirmed by coronary angiography. Right margin of ischemic region in the basal short axial image was -36 +/- 17 degrees and left margin was -128 +/- 75 degrees. In 28 pts of 43 pts left margin lied beyond -120 degrees. From the results it was concluded that in most cases basal inferior wall was perfused by septal branches from LAD. In 6 pts with midportion lesion situated proximal to the first diagonal branch and in 12 pts with midportion lesion situated proximal to the second diagonal branch ischemic region in the apical portion was noted at both septum and anterolateral wall. Critical short axial image, in which right margin of ischemic region shifted from plus to minus area, was the 3.2nd short axial image in the former group and the 5.2nd in the latter group (p < 0.01). In 10 pts with midportion lesion situated distal to the large first diagonal branch, ischemic region was noted in septal wall and not in anterolateral wall. It was concluded that right margin of ischemic region in the basal coronal image was the most useful sign for predicting midportion lesion and left margin for dominance between LAD and right coronary artery and that apical anterolateral ischemia was sign for LAD lesion involving diagonal branch. Critical short axial image was useful for determining whether the lesion was situated proximal or distal to the first diagonal branch and whether the lesion was situated proximal to the second diagonal branch.

[Noninvasive estimation of site of lesion of left anterior descending artery with stress 201Tl myocardial SPECT images]

Noninvasive estimation of site of lesion of left anterior descending artery (LAD) is important because of high morbidity of LAD lesion. Utility of stress 201Tl myocardial SPECT images for predicting site of LAD lesion characteristics of ischemic region induced by LAD lesion in the basal coronal image were studied in 53 patients with localized significant LAD lesion. Right margin of ischemic region at basal plane of SPECT images was determined by circumferential maximum count profile analysis of stress 201Tl myocardial images. Right margin of ischemic region induced by the just proximal lesion was 21 +/- 11 degrees, that by proximal lesion was -6 +/- 10 degrees and that by mid portion was -36 +/- 17 degrees. Sensitivity of right margin of ischemic region 0 for just proximal lesion was 100% (20/20) and that of right margin of ischemic region 0 for mid portion lesion was 100% (18/18). These results showed the possibility of detecting site of LAD lesion by stress 201Tl myocardial SPECT images.

[In-111 antimyosin-Fab uptake in contractile myocardium of old myocardial infarction]

As In-111 monoclonal antimyosin antibody (AM) has been thought to bind with human myosin exposed in myocytes irreversibly damaged by an ischemic event. The AM uptake in contractile myocardium after acute myocardial infarction was studied. AM planar images were obtained 48 hours later after injection of 74 MBq of AM in 6 patients 2-10 months later after acute myocardial infarction. Mean ejection fraction was 66% (75-58). Myocardial AM uptake was definite in comparison with mediastinum uptake in all 6 patients and mean heart lung ratio was 2.3 +/- 0.5. AM SPECT images and T1-201 SPECT images were obtained with dual mode. Mean T1-201 uptake at the region of maximal AM uptake was 77% (90-63). Echocardiography showed contractility of the region. Mean maximal AM uptake in the anterior wall region was 83% (100-75) and mean T1-201 uptake at the region was 81% (90-75) and shortening rate of the region was 34% (52-25). The region with AM uptake has been shown to correlate with the region salvaged from necrosis by reperfusion. It has been shown that AM was uptaken in contractile myocardium in chronic phase of acute myocardial infarction. It was suspected that myocardium under severe ischemic event may be salvaged by reperfusion therapy and retain contractility in chronic phase, however irreversible damage, which permit AM uptake, may remain in myocardium.

[Utility of rest Tl-201 myocardial SPECT images for estimating myocardial viability]

Rest Tl-201 myocardial SPECT images were underwent in 19 patients with anterior wall myocardial infarction under PTCR one month after the onset of acute myocardial infarction. The relationship between shortening rate (SR) of the left ventricle estimated by radial method and corresponding %Tl-201 uptake obtained by circumferential profile analysis was studied. For each patients 10 points on the anterior wall were taken into consideration. Seven patients showed depressive flat profile curve and 12 patients showed slant curve, in which %Tl-201 uptake continuously decreased from base to apex. Well correlation was obtained between SR and %Tl-201 uptake (SR = -41.2 +/- 1.03% Tl-201 uptake, r = 0.54, p less than 0.001). Average %Tl-201 uptake corresponding to SR = 0 was 46.3 + 6.8% (36-58). The sensitivity of %Tl-201 uptake greater than or equal to 60% for SR greater than or equal to 20% was 97% (87/90) and specificity was 69% (31/45). Tl-201 myocardial SPECT images were useful for estimating myocardial viability and %Tl-201 uptake was one of excellent parameters for quantitatively estimating myocardial viability.

[Interesting PYP, Tl-201, MIBG and AM myocardial SPECT images in a patient under successful reperfusion therapy]

Various types of radiopharmacons such as Tl-201, Tc-99m pyrophosphate (PYP), I-123 Metaiodobenzylguanidine (MIBG) and In-111 antimyosin Fab (AM), were applied to a patients under successful reperfusion therapy. In the patient QS waves in precordial leads and elevated serum enzyme activity was noted, however well anterior wall movement was maintained in chronic phase. At 4th hospital day PYP uptake was noted at apical region and basal anteroseptal region. Most portion of PYP uptake was overlapped by Tl-201 uptake. Depressed Tl-201 uptake in subacute phase improved. In chronic phase depressed MIBG uptake was noted at the region corresponding to the abnormal region in acute phase. Then months after the ischemic event AM uptake was noted at the region which maintained contractility. From these findings it was concluded as followings. Salvaged jeopardized myocardium remained ischemia in subacute phase. The lesions noted in the MIBG images showed depressed myocardial norepinephrine activity. This suggested that sympathetic nervous function was damaged by severe ischemia and the depressed sympathetic nervous function persisted long after myocardial perfusion had been restored. From abnormal AM uptake ten months after ischemic event it was suspected that myocardial cell membrane damage caused by severe ischemia might be persistent at the region which maintained contractility. Radioisotope image was useful to study pathological myocardium due to ischemic event.

[Characteristics of Tl-201 myocardial SPECT images of patients with coronary artery lesion of diagonal branch]

Noninvasive detection of coronary artery lesion of diagonal branch is important. Utility of Tl-201 myocardial SPECT images for this purpose was studied in 9 patients with angina pectoris and 4 patients with myocardial infarction, in whom localized stenosis more than 75% was noted at diagonal branch. Position of basal margin of abnormal region in the coronal images lay between -30 degree and 30 degree and basal abnormal region was very narrow. Width of mid portion of abnormal region lay from 5 degree to 70 degree. Abnormal region due to diagonal branch was not noted in septal region. These results showed the utility of Tl-201 myocardial SPECT images for detecting coronary artery lesion of diagonal branch.

[Tl-201 myocardial images in a patient with dialated cardiomyopathy, who finally received heart transplantation]

The patient responded to treatment at the first onset of heart failure but gradually became irresponsive to treatment, experiencing fatigue and malaise as the chief complaints and suffering from gradually progressive decrease in exercise capacity and body weight. Dose of DOA gradually increased to maintain well clinical state of the patient. Unusual for heart failure, he had bradycardia as the basal rhythm without showing a tendency for tachycardia. Cardiac catheterization revealed pulmonary hypertension and low cardiac output, however, left ventricular ejection fraction was 37%. There were no notable changes in ultrasonic cardiogram or CTR through the clinical course. Tl-201 myocardial images and pulmonary perfusion images showed gradual worsening corresponding to progressive worsening of clinical state. From these findings, the patient was determined as a candidate for heart transplantation.

[Myocardial viability in QS region after PTCR]

Myocardial viability after PTCR in patients with first anterior myocardial infarction was studied one month after the onset of acute myocardial infarction by profile curve of Tl-201 coronal myocardial SPECT images. Patients were devided into two groups according to left ventricular ejection fraction (EF), i.e. group A (EF more than 50%; 11 cases , EF; 62 +/- 10%) and group B (EF less than 50%; 9 cases, EF; 40 7%). Patients in group A showed an increase in serum GOT at the acute phase of acute myocardial infarction (322 +/- 182IU), decreased %Tl-201 uptake in QS region (65 +/- 7%) significantly less than the normal range, large size of region of infarction (214 +/- 83 degree) and abnormal QS in ECG (V1-3QS; 2 cases, V1-4QS; 8 cases, V1-5QS; 1 case). Improvement of wall motion in region of infarction was noted in 9 cases. Patients in group B showed an increase in serum GOT (651 +/- 382 IU p; ns), %Tl-201 uptake in QS region (48 +/- 7% p greater than 0.001) significantly less than the %Tl-201 uptake in group A, size of defects (243 +/- 45 p; ns) and abnormal QS in ECG (V1-3QS; 1 case, V1-4QS; 7 cases V1-5QS; 1 case). Improvement of wall motion was noted in 2 cases. The study showed that %Tl-201 uptake in region of infarction in patients with well EF was significantly more than that in patients with depressed EF. Mechanism of maintaining well EF after PTCR was suggested as the following, i.e. in the region released from severe ischemic attack part of myocardium resulted in necrosis, accompanying elevation of serum enzyme and appearance of QS, though part of myocardium might be salvaged from necrosis and contribute to EF in chronic phase. It has been generally thought that abnormal QS waves noted in anterior chest leads of ECG in chronic phase indicated transmural myocardial infarction in the anterior region. From this study it was concluded that QS region with %Tl-201 more than 50% did not generally correspond to transmural myocardial necrosis and that for estimation of myocardial viability %Tl-201 uptake might be more useful than ECG.

[Study of sympathetic nervous function under effort induced ischemia in patients with angina pectoris with I-123 metaiodobenzylguanidine (MIBG) myocardial SPECT images]

I-123 metaiodobenzylguanidine (MIBG) is a norepinephrine analog, which can be used to study the sympathetic nervous function of the heart. With MIBG myocardial SPECT images sympathetic nervous function under effort induced ischemia were studied in 18 patients with significant coronary artery lesions. In 5 patients with effort induced ischemic region in stress T1-201 myocardial images rest MIBG images were collected and then exercise stress test was performed. Patients continued exercising for 3 minutes after onset of symptom. Post-stress MIBG images were collected. Definite ischemic region was noted in stress Tl-201 myocardial images, however no differences were noted between rest and post-stress MIBG images. These results suggested that exercise induced ischemia did not enhance release of uptaken MIBG. In 13 patients with significant coronary artery lesions symptom-limited exercise stress test was performed MIBG and Tl-201 were simultaneously injected at onset of symptom and patients continued exercising for an additional one minute. In 6 cases (46%, 6/13) MIBG defects with Tl-201 uptake were noted. These results showed that exercise induced ischemia depressed net MIBG uptake and that sympathetic nervous function (MIBG images) may be more sensitive to ischemic damage than muscle (Tl-201 images). It is suggested that exercise induced ischemia depressed reuptake of norepinephrine at sympathetic nervous endings. MIBG myocardial SPECT images may be useful for evaluating sympathetic nervous function under ischemia.

[Characteristics of stress Tl-201 myocardial SPECT images in patients with coronary artery lesion of just proximal portion of left anterior descending artery or high lateral branch]

Noninvasive detection of coronary artery lesion of just proximal portion of left anterior descending artery (LAD) is important because of its high morbidity. It is angiographically difficult to distinguish LAD and high lateral branch (HL). Utility of stress Tl-201 myocardial SPECT images for this purpose characteristics of ischemic region induced by coronary artery lesion of just proximal portion of LAD or HL were studied in 15 patients with localized stenosis more than 75% at just proximal portion of LAD and 5 patients with localized stenosis more than 75% at HL. Width of ischemic region at basal plane of SPECT images was determined by circumferential maximum count profile analysis of stress Tl-201 myocardial images. Width of ischemic region induced by coronary artery lesion of just proximal portion of LAD was 168 +/- 34 degrees. Right margin of ischemic region was 20 +/- 6 degrees and in 10 of 15 patients right margin lay between 20 degrees and 60 degrees. Left margin was -146 +/- 40 degrees and 7 patients with left margin more than -150 degrees showed left dominant coronary artery. Width of ischemic region induced by coronary lesion of HL was 64 +/- 10 degrees. Right margin of ischemic region was 78 +/- 10 degrees and left margin was 14 +/- 10 degrees. These results showed the possibility of detecting coronary artery lesion of just proximal portion of LAD and lesion of HL by stress Tl-201 myocardial SPECT images.

Definition of mixing rate of indicator by indicator dilution method: evaluation of relationship between mixing rate of indicator and cardiac output determination

It is generally agreed that complete mixing of the indicator is one of the most important factors of the indicator dilution method, however, no clear definition of the mixing state has been established. We established a formula for the mixing rate of the indicator by the indicator dilution method, using the concept of entropy in the information theory, and compared the mixing rate of indocyanine green in one mixing chamber (left ventricle) with that in the two mixing chamber system (including the aortic system). The mixing rate of the indicator (M) is shown as M(%) = 100 H/Hcm = -100 (lk sigma ni = 1 Ci + log Ci + log k) (l & k: correction factors in each dye dilution curve, C: mean concentration of the indicator in the region). Left heart and aortic catheterizations by retrograde femoral and carotid artery approach were performed in five anesthetized dogs. Simultaneous dye dilution curves were recorded at the aortic root and at the bifurcation of the abdominal aorta, following the injection of indocyanine green (2.5 mg/1 ml of indocyanine green for each injection) by impulse into the left ventricle at the endsystole, triggered on the R wave of ECG, using the automatic injector devised by the authors. Twenty-five pairs of dye dilution curves were obtained by simultaneous recording in the aortic root and the abdominal aorta under several hemodynamic conditions, and the cardiac output, mean circulation time and the mixing rate of the indicator were determined.(ABSTRACT TRUNCATED AT 250 WORDS)