Juergen vom Dahl

Clinical outcome of patients with advanced coronary artery disease after viability studies with positron emission tomography

OBJECTIVE The aim of this study was to determine the prognostic significance of perfusion-metabolism imaging in patients undergoing positron emission tomography for myocardial viability assessment. BACKGROUND Positron emission tomography using nitrogen-13 ammonia and 18fluorodeoxyglucose to assess myocardial blood flow and metabolism has been shown to predict improvement in wall motion after coronary artery revascularization. The prognostic implications of metabolic imaging in patients with advanced coronary artery disease have not been investigated. METHODS Eighty-two patients with advanced coronary artery disease and impaired left ventricular function underwent positron emission tomographic imaging between August 1988 and March 1990 to assess myocardial viability before coronary artery revascularization. RESULTS Forty patients underwent successful revascularization. Patients who exhibited evidence of metabolically compromised myocardium by positron emission tomography (decreased blood flow with preserved metabolism) who did not undergo subsequent revascularization were more likely to experience a myocardial infarction, death, cardiac arrest or late revascularization due to development of new symptoms than were the other patient groups (p less than 0.01). Concordantly decreased flow and metabolism in segments of previous infarction did not affect outcome in patients with or without subsequent revascularization. Those with a compromised myocardium who did undergo revascularization were more likely to experience an improvement in functional class than were patients with preoperative positron emission tomographic findings of concordant decrease in flow and metabolism. CONCLUSIONS Positron emission tomographic myocardial viability imaging appears to identify patients at increased risk of having an adverse cardiac event or death. Patients with impaired left ventricular function and positron emission tomographic evidence for jeopardized myocardium appear to have the most benefit from a revascularization procedure.

Influence of a platelet GPIIb/IIIa receptor antagonist on myocardial hypoperfusion during rotational atherectomy as assessed by myocardial Tc-99m sestamibi scintigraphy

OBJECTIVES This study evaluated the effect of the glycoprotein IIb/IIIa (GPIIb/IIIa) antagonist abciximab on myocardial hypoperfusion during percutaneous transluminal rotational atherectomy (PTRA). BACKGROUND PTRA may cause transient ischemia and periprocedural myocardial injury. A platelet-dependent risk of non-Q-wave infarctions after directional atherectomy has been described. The role of platelets for the incidence and severity of myocardial hypoperfusion during PTRA is unknown. METHODS Seventy-five consecutive patients with complex lesions were studied using resting Tc-99m sestamibi single-photon emission computed tomography prior to PTRA, during, and 2 days after the procedure. The last 30 patients received periprocedural abciximab (group A) and their results were compared to the remaining 45 patients (group B). For semiquantitative analysis, myocardial perfusion in 24 left ventricular regions was expressed as percentage of maximal sestamibi uptake. RESULTS Baseline characteristics did not differ between the groups. Transient perfusion defects were observed in 39/45 (87%) patients of group B, but only in 10/30 (33%) patients of group A (p < 0.001). Perfusion was significantly reduced during PTRA in 3.3 +/- 2.5 regions in group B compared to 1.4 +/- 2.5 regions in group A (p < 0.01). Perfusion in the region with maximal reduction during PTRA in groups B and A was 76 +/- 15% and 76 +/- 15% at baseline, decreased to 56 +/- 16% (p < 0.001) and 67 +/- 14%, respectively, during PTRA (p < 0.01 A vs. B), and returned to 76 +/- 15% and 80 +/- 13%, respectively, after PTRA. Nine patients in group B (20%) and two patients in group A (7%) had mild creatine kinase and/or troponin t elevations (p = 0.18). Patients with elevated enzymes had larger perfusion defects than did patients without myocardial injury (4.2 +/- 2.7 vs. 2.3 +/- 2.5 regions, p < 0.05). CONCLUSIONS These data indicate that GPIIb/IIIa blockade reduces incidence, extent and severity of transient hypoperfusion during PTRA. Thus, platelet aggregation may play an important role for PTRA-induced hypoperfusion.

Myocardial viability assessment by endocardial electroanatomic mapping: comparison with metabolic imaging and functional recovery after coronary revascularization

OBJECTIVES The objective of this study was to compare electroanatomic mapping for the assessment of myocardial viability with nuclear metabolic imaging using positron emission computed tomography (PET) and with data on functional recovery after successful myocardial revascularization. BACKGROUND Animal experiments and first clinical studies suggested that electroanatomic endocardial mapping identifies the presence and absence of myocardial viability. METHODS Forty-six patients with prior (> or =2 weeks) myocardial infarction underwent fluorine-18 fluorodeoxyglucose (FDG) PET and Tc-99m sestamibi single-photon emission computed tomography (SPECT) before mapping and percutaneous coronary revascularization. The left ventricular endocardium was mapped and divided into 12 regions, which were assigned to corresponding nuclear regions. Functional recovery using the centerline method was assessed in 25 patients with a follow-up angiography. RESULTS Regional unipolar electrogram amplitude was 11.0 mV +/- 3.6 mV in regions with normal perfusion, 9.0 mV +/- 2.8 mV in regions with reduced perfusion and preserved FDG-uptake and 6.5 mV +/- 2.6 mV in scar regions (p < 0.001 for all comparisons). At a threshold amplitude of 7.5 mV, the sensitivity and specificity for detecting viable (by PET/SPECT) myocardium were 77% and 75%, respectively. In infarct areas with electrogram amplitudes >7.5 mV, improvement of regional wall motion (RWM) from -2.4 SD/chord +/- 1.0 SD/chord to -1.5 SD/chord +/- 1.1 SD/chord (p < 0.01) was observed, whereas, in infarct areas with amplitudes <7.5 mV, RWM remained unchanged at follow-up (-2.3 SD/chord +/- 0.7 SD/chord to -2.4 SD/chord +/- 0.7 SD/chord). CONCLUSIONS These data suggest that the regional unipolar electrogram amplitude is a marker for myocardial viability and that electroanatomic mapping can be used for viability assessment in the catheterization laboratory.

Comparison of thallium-201 single-photon emission tomography after rest injection and fluorodeoxyglucose positron emission tomography for assessment of myocardial viability in patients with chronic coronary artery disease

This prospective study in 42 patients with chronic coronary artery disease and severe wall motion abnormalities (sWMA) on cineventriculography (24 patients with previous myocardial infarction; ejection fraction, 45%±13%) was designed to compare myocardial thallium-201 uptake after rest injection and normalized fluorodeoxyglucose (18FDG) uptake (after oral glucose load) for assessment of a rest 201Tl protocol to evaluate myocardial viability. The left ventricle was divided into the supply territory of the left anterior descending coronary artery (LAD) and the lateral wall and posterior territory (inferior, posterior and posteroseptal segments) because of the high variability of left circumflex and right coronary artery supply territories. Segmental 201Tl uptake in single-photon emission tomography (SPET) and segmental normalized 18FDG uptake (13 segments per patient) showed a close linear relationship in the LAD territory (r=0.79) and in the lateral wall (r=0.77), while the correlation in the posterior territory was considerably lower (r=0.52). 201Tl/18FDG concordance was defined as an 18FDG uptake exceeding 201Tl uptake by < 20%. Discordance was assumed if 18FDG exceeded 201Tl uptake by at least 20%. Concordant results were shown by 81% (439/541) of segments. In segments with severe 201Tl reduction (≤ 50% of peak, n=78) discordance was observed in 10% of segments in the LAD territory and lateral wall (n=62) and in 44% of segments in the posterior territory (n=16). In segments with moderate 201Tl reduction (51%−75%, n=205) discordance occured in 12% (LAD and lateral wall, n=126) or 46% (posterior territory, n=79) of segments, respectively. Severe defects were defined as the entire area with 201Tl uptake ≤50% within a defined territory. Discordance was observed in 6/43 (14%) of these. Of 90 areas with sWMA on cineventriculography, 12 showed discordant results. Ten of these 12 discordant areas affected septum or posterior wall. In areas with normal wall motion or only mild hypokinesis, discordance occured in the septum or posterior wall in 22% whereas the figure for the anterior or lateral wall was only 2%. These results point to a significant role of photon attenuation in 201Tl SPET imaging in the septum and posterior wall. It is concluded that 201Tl SPET using a rest protocol identifies viable myocardium in the supply area of the LAD and in the lateral wall with high accuracy compared to 18FDG positron emission tomography while disordance in the posterior territory may be governed by photon attenuation in the SPET study rather than by a pathophysiological difference.

Myocardial Bridging in Absence of Coronary Artery Disease: Proposal of a New Classification Based on Clinical-Angiographic Data and Long-Term Follow-Up

Background: There is no widely accepted classification to guide therapy in patients with symptomatic myocardial bridging (MB). Methods: A retrospective analysis of 157 patients with chest pain, angiographic MB of the left anterior descending artery without obstructive coronary artery disease (CAD) was performed. Patients were evaluated for clinical symptoms, objective signs of ischemia by stress test, intracoronary Doppler flow measurement and coronary flow reserve. 100 patients without CAD or MB served as controls. Results: There was no difference in clinical symptoms and objective signs of ischemia between controls and patients with MB. The length of MB was 22.6 ± 7.8 mm, maximal systolic luminal diameter reduction 71 ± 16%, and maximal mid-diastolic luminal reduction 34.7 ± 13% as demonstrated by quantitative coronary angiography (QCA). Intracoronary Doppler showed significantly increased average peak flow velocity (APV), average systolic peak velocity (ASPV), average diastolic peak flow velocity (ADPV), and maximal peak velocity (MPV) in MB versus proximal and distal segments at rest and after maximal vasodilatation (p < 0.001 for all parameters). Coronary flow reserve was significantly higher proximally (2.9 ± 0.9) compared with segments distal to the MB (2.0 ± 0.6, p < 0.01). We propose a new MB classification for symptomatic patients with MB:Type A:incidental finding on angiography, no objective signs of ischemia; Type B: objective signs of ischemia, and Type C: with or without objective signs of ischemia and altered intracoronary hemodynamics (by QCA/CFR/intracoronary Doppler). 5-Year follow-up data based on this classification showed that types B and C responded well to β-blockers or calcium channel antagonists. Patients with type C refractory to medical therapy were treated with stenting of the MB. Conclusion: Patients with MB without CAD did not have a higher prevalence of chest pain or abnormal non-invasive stress tests compared to patients without CAD or MB. Intracoronary hemodynamic measurement is a novel approach that may be valuable in defining the functional significance of MB. We propose a classification of symptomatic patients with MB without CAD using non-invasive and invasive parameters to guide therapeutic choices.

Fate of the resting perfusion defect as assessed with technetium-99m methoxy-isobutyl-isonitrile single-photon emission computed tomography after successful revascularization in patients with healed myocardial infarction

It is concluded that in patients with healed myocardial infarction, MIBI uptake at rest underestimates myocardial viability and may improve significantly if blood flow is restored. Patients with MIBI defects at rest may therefore take advantage of revascularization.

Insufficient tissue ablation by rotational atherectomy leads to worse long‐term results in comparison with balloon angioplasty alone for the treatment of diffuse in‐stent restenosis: Insights from the intravascular ultrasound substudy of the ARTIST randomized multicenter trial

The ARTIST trial demonstrated a worse outcome for patients with in‐stent restenosis (ISR) treated with rotational atherectomy (RA) and adjunctive balloon angioplasty (PTCA) as compared to PTCA alone. This intravascular ultrasound (IVUS) substudy compares effects of lumen enlargement and examines reasons for failure of RA in this setting. IVUS (n = 56) was performed after each interventional step and at follow‐up. Volumetric lumen gain measured 79 ± 68 mm3 after PTCA (13 ± 4 atm) as compared to 44 ± 26 mm3 after RA and adjunctive PTCA (7 ± 3 atm; P < 0.0001). RA itself enlarged lumen by only 19 ± 17 mm3 and stent volume was 47% smaller as compared to high‐pressure PTCA. Low‐pressure strategy after RA did not prevent tissue growth during follow‐up (19 ± 25 vs. 36 ± 38 mm3; RA vs. PTCA; P = 0.09). Consequently, net lumen gain after PTCA was 82% higher compared to RA (46 ± 54 vs. 25 ± 24 mm3; P = 0.09). Further stent expansion is the key mechanism to achieve luminal gain by PTCA of ISR. Neointimal ablation by RA has only minor effects. Low‐pressure PTCA does not prevent recurrent tissue growth and failed for treatment of ISR due to insufficient stent expansion. Catheter Cardiovasc Interv 2003;60:25–31.

Factors influencing outcome of regional wall motion after successful elective single-vessel percutaneous transluminal coronary angioplasty

BackgroundThe long-term outcome of impaired regional myocardial contractility after successful single vessel percutaneous transluminal coronary angioplasty (PTCA) was angiographically evaluated. MethodsThe ventriculograms prior to PTCA and at mid-term follow-up of 250 consecutive patients with successful elective single-vessel PTCA were analyzed. One hundred of 250 patients demonstrated regional wall motion abnormalities in the PTCA vessel-dependent region by visual analysis before PTCA. The study group comprised 66 of these 100 patients (four women, 62 men, mean age 52 ± 8 years, 50 left anterior descending artery stenoses and 16 right coronary artery stenoses) in whom paired ventriculograms could be analyzed quantitatively by the centerline method. Results: Ejection fraction increased from 58% ± 7% to 60% ± 7%. Hypokinesis in the central distribution area of the PTCA vessel decreased from −1.3 ± 0.8 to −0.9 ± 0.7 standard deviations/chord (SD/chord) (P < 0.001). The circumferential extent (percentage of left ventricular contour) of hypokinesis worse than −2 SD decreased significantly by 45% at follow-up. Left ventricular function improved the most in patients with more severe depressed function or more severe stenosis at baseline. Previous (more than 6 weeks old) myocardial infarction (40% of patients) did not preclude functional improvement. Restenosis occurred in 36% of patients, but did not influence function significantly. ConclusionsThe magnitude of left ventricular functional recovery after successful PTCA in patients with chronic ischemia is related to the severity of resting dysfunction and of stenosis prior to treatment. Patients with severe hypokinesis as well as with akinesis have the potential to improve, even in the presence of previous infarction.

Effects of left ventricular volume and ejection on myocardial blood flow measured by oxygen-15 water positron emission tomography in coronary heart disease.

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