Sheridan N. Meyers

Unrecognized Non-Q-Wave Myocardial Infarction: Prevalence and Prognostic Significance in Patients with Suspected Coronary Disease

Using delayed-enhancement cardiovascular magnetic resonance, Han Kim and colleagues show that in patients with suspected coronary disease the prevalence of unrecognized myocardial infarction without Q-waves is more than 3-fold higher than that with Q-waves and predicts subsequent mortality.

Accurate Three-Dimensional Reconstruction of Intravascular Ultrasound Data Spatially Correct Three-Dimensional Reconstructions

BACKGROUND The geometrical accuracy of conventional three-dimensional (3D) reconstruction methods for intravascular ultrasound (IVUS) data (coronary and peripheral) is hampered by the inability to register spatial image orientation and by respiratory and cardiac motion. The objective of this work was the development of improved IVUS reconstruction techniques. METHODS AND RESULTS We developed a 3D position registration method that identifies the spatial coordinates of an in situ IVUS catheter by use of simultaneous ECG-gated biplane digital cinefluoroscopy. To minimize distortion, coordinates underwent pincushion correction and were referenced to a standardized calibration cube. Gated IVUS data were acquired digitally, and the spatial locations of the imaging planes were then transformed relative to their respective 3D coordinates, rendered in binary voxel format, resliced, and displayed on an image-processing workstation for off-line analysis. The method was tested by use of phantoms (straight tube, 360 degrees circle, 240 degrees spiral) and an in vitro coronary artery model. In vivo feasibility was assessed in patients who underwent routine interventional coronary procedures accompanied by IVUS evaluation. Actual versus calculated point locations were within 1.0 +/- 0.3 mm of each other (n = 39). Calculated phantom volumes were within 4% of actual volumes. Phantom 3D reconstruction appropriately demonstrated complex morphology. Initial patient evaluation demonstrated method feasibility as well as errors if respiratory and ECG gating were not used. CONCLUSIONS These preliminary data support the use of this new method of 3D reconstruction of vascular structures with use of combined vascular ultrasound data and simultaneous ECG-gated biplane cinefluoroscopy.

Correspondence Between the 17-Segment Model and Coronary Arterial Anatomy Using Contrast-Enhanced Cardiac Magnetic Resonance Imaging

OBJECTIVES The purpose of this study was to investigate the correspondence between the coronary arterial anatomy and supplied myocardium based on the proposed American Heart Association 17-segment model. BACKGROUND Standardized assignment of coronary arteries to specific myocardial segments is currently based on empirical assumptions. METHODS A cardiac magnetic resonance study was performed in 93 subjects following acute myocardial infarction treated with primary percutaneous coronary intervention. Two observers blindly reviewed all angiograms to examine the location of the culprit lesion and coronary dominance. Two additional observers scored for the presence of cardiac magnetic resonance hyperenhancement (HE) on a 17-segment model. Segments were divided based on anatomical landmarks such as the interventricular grooves and papillary muscles. RESULTS In a per-segment analysis, 23% of HE segments were discordant with the empirically assigned coronary distribution. Presence of HE in the basal anteroseptal, mid-anterior, mid-anteroseptal, or apical anterior wall was 100% specific for left anterior descending artery occlusion. The left anterior descending artery infarcts frequently involved the mid-anterolateral, apical lateral, and apical inferior walls. No segment was 100% specific for right coronary artery or left circumflex artery (LCX) occlusion, although HE in the basal anterolateral wall was highly specific (98%) for LCX occlusion. Combination of HE in the anterolateral and inferolateral walls was 100% specific for a LCX occlusion, and when extended to the inferior wall, was also 100% specific for a dominant or codominant LCX occlusion. CONCLUSIONS Four segments were completely specific for left anterior descending artery occlusion. No segment can be exclusively attributed to the right coronary artery or LCX occlusion. However, analysis of adjacent segments increased the specificity for a given coronary occlusion. These findings bring objective evidence in the appropriate segmentation of coronary arterial perfusion territories and assist accurate assignment of the culprit vessel in various imaging modalities.

Drug-Eluting Versus Bare-Metal Stents in Unprotected Left Main Coronary Artery Stenosis: A Meta-Analysis

OBJECTIVES We undertook a meta-analysis to assess outcomes for drug-eluting stents (DES) and bare-metal stents (BMS) in percutaneous coronary intervention for unprotected left main coronary artery (ULMCA) stenosis. BACKGROUND Uncertainty exists regarding the relative performance of DES versus BMS in percutaneous coronary intervention for unprotected left main coronary stenosis. METHODS Of a total of 838 studies, 44 met inclusion criteria (n = 10,342). The co-primary end points were mortality, myocardial infarction (MI), target vessel/lesion revascularization (TVR/TLR), and major adverse cardiac events (MACE: mortality, MI, TVR/TLR). RESULTS Event rates for DES and BMS were calculated at 6 to 12 months, at 2 years, and at 3 years. Crude event rates at 3 years were mortality (8.8% and 12.7%), MI (4.0% and 3.4%), TVR/TLR (8.0% and 16.4%), and MACE (21.4% and 31.6%). Nine studies were included in a comparative analysis (n = 5,081). At 6 to 12 months the adjusted odds ratio (OR) for DES versus BMS were: mortality 0.94 (95% confidence interval [CI]: 0.06 to 15.48; p = 0.97), MI 0.64 (95% CI: 0.19 to 2.17; p = 0.47), TVR/TLR 0.10 (95% CI: 0.01 to 0.84; p = 0.01), and MACE 0.34 (95% CI: 0.15 to 0.78; p = 0.01). At 2 years, the OR for DES versus BMS were: mortality 0.42 (95% CI: 0.28 to 0.62; p < 0.01), MI 0.16 (95% CI: 0.01 to 3.53; p = 0.13), and MACE 0.31 (95% CI: 0.15 to 0.66; p < 0.01). At 3 years, the OR for DES versus BMS were: mortality 0.70 (95% CI: 0.53 to 0.92; p = 0.01), MI 0.49 (95% CI: 0.26 to 0.92; p = 0.03), TVR/TLR 0.46 (95% CI: 0.30 to 0.69; p < 0.01), and MACE 0.78 (95% CI: 0.57 to 1.07; p = 0.12). CONCLUSIONS Our meta-analysis suggests that DES is associated with favorable outcomes for mortality, MI, TVR/TLR, and MACE as compared to BMS in percutaneous coronary intervention for unprotected left main coronary artery stenosis.

Angiographically silent left main disease detected by intravascular ultrasound: a marker for future adverse cardiac events

BACKGROUND Concomitant moderate obstructive left main (LM) disease is associated with future cardiac events and poor prognosis in patients undergoing percutaneous intervention (PCI). Whether prognosis is similarly effected by LM disease not detected by angiography, but evident on intravascular ultrasound (IVUS) imaging, is not known. The purpose of this study was to evaluate the long-term prognosis of patients with angiographically insignificant LM coronary artery disease undergoing PCI. METHODS AND RESULTS One hundred and seven consecutive patients undergoing PCI with angiographically normal or mild LM disease had 2- and 3-dimensional IVUS imaging. IVUS images were digitized, and 3-dimensional reconstruction was performed. Percent diameter and area stenosis by angiography were 4.8% +/- 3.5% and 18.2% +/- 9.8%, respectively. IVUS mean luminal area and area stenosis were 17.9 +/- 5.6 mm2 and 30.2% +/- 14.7%, respectively. Long-term follow-up was available in 102 (95%) patients at a median of 29 (range 8-52) months. Major adverse cardiac events, defined as death (6), myocardial infarction (4), repeat PCI (13), or CABG (16), were associated with female sex (P =.04), diabetes (P =.02), angiographic minimum lumen diameter (P =.04), and IVUS minimum (P =.01) and mean (P =.01) lumen area. Multivariate predictors of late cardiac events were diabetes (hazard ratio 2.69, P =.014) and minimum lumen area by IVUS (hazard ratio 0.59, P =.015). CONCLUSIONS Despite being angiographically silent, LM disease detected by IVUS is an independent predictor of cardiac events and may serve as a marker for such events. These data extend the spectrum of LM disease severity and its relationship to cardiac prognosis in patients undergoing PCI.

Arterial imaging with a new forward-viewing intravascular ultrasound catheter, II. Three-dimensional reconstruction and display of data.

BackgroundCurrent intravascular ultrasound (IVUS) catheters provide transverse imaging at the level of the ultrasound transducer. This limits imaging to large-diameter segments without critical atherosclerotic narrowings. We have developed a prototype 20-MHz forward-viewing IVUS catheter that provides two-dimensional sector imaging distal to the catheter tip. A present limitation of this technique is that the catheter must be manually rotated to obtain multiple longitudinal views required to integrate the segment into a three-dimensional matrix. To overcome this, we have developed an algorithm that reconstructs these multiple two-dimensional forward-viewing IVUS images into a three-dimensional matrix for more complete depiction of the segment distal to the ultrasound catheter. This algorithm allows display and multidimensional slicing of the three-dimensional reconstruction. Methods and ResultsTo test our algorithms, five arterial segments (three canine aortas, two human femoral arteries) were evaluated in vitro. In each segment, 36 forward-viewing longitudinal slices were collected, digitized, processed, and reoriented to produce a three-dimensional reconstruction (3DR) matrix. The matrix data were sliced into parallel transverse sections and compared with morphometric interpretation of histological sections (Histo). As a result, image data could be reconstructed for a distance of 2.0 cm ahead of the catheter. 3DR easily demonstrated wall and luminal morphology and provided transverse IVUS images comparable to the histological specimens. A good correlation was noted between Histo- and 3DR-determined luminal diameters (LD) and luminal areas: 3DR LD=1.4 Histo LD−0.4, r = .86; 3DR LD=0.7±0.20 cm (mean±SD); and Histo LD=0.7±0.13 cm. ConclusionsThese preliminary data demonstrate the feasibility of 3DR of forward-viewing IVUS data. This method allows rapid, detailed analysis of diseased arterial segments previously unavailable with standard IVUS and may permit better targeting of interventional techniques.

Arterial imaging with a new forward-viewing intravascular ultrasound catheter, I. Initial studies.

BackgroundIntravascular ultrasound (IVUS) of arteries is limited by the inability of current instruments to visualize beyond the catheter tip. We have developed a prototype 4-mm-diameter forward-viewing IVUS catheter (Cardiovascular Imaging Systems, Sunnyvale, Calif) that has the ability to provide B-mode cross-sectional ultrasound data for a distance of up to 2 cm distal to the catheter tip. Methods and ResultsTo study the utility of this device, a 20-MHz forward-viewing IVUS catheter was used to examine 13 arterial segments (5 human femoral arteries, 1 human carotid artery, 7 canine arteries) in vitro and 1 phantom. After imaging, all data were compared with histology (Histo). In all cases, the IVUS catheter provided forward-viewing images corresponding to the arterial geometry and demonstrated vascular landmarks and atherosclerotic lesions. There was a good correlation between Histo-determined luminal diameters (LD) and IVUS-determined diameters for a distance of 14 mm ahead of the catheter tip: IVUS LD= 1.0 Histo LD+ 1.3 (r = .87). ConclusionsThese preliminary data suggest that a forward- viewing IVUS catheter is feasible, accurate, and useful for evaluation of arterial geometry distal to the catheter tip.

Acquired cyanotic heart disease secondary to traumatic tricuspid regurgitation: Case report with a review of the literature

A case of traumatic tricuspid insufficiency leading to right atrial enlargement and to a patent foramen ovale with right to left shunting is presented. Six similar cases previously reported are reviewed. The time course of clinical deterioration was related to the type of tricuspid valve damage incurred. Papillary muscle rupture led to surgery within a year, whereas less severe chordal damage allowed a more benign course that lasted from 10 to 25 years from the time of injury to the time of surgery. Surgical repair of the incompetent tricuspid valve and closure of the atrial septal defect led to significant improvement. The diagnostic usefulness of radionuclide imaging and echocardiography is demonstrated in this case. A mechanism of right to left interatrial shunting in the presence of normal pulmonary arterial pressures is proposed; this invokes phasic increases in right atrial pressure from tricuspid insufficiency and streaming of blood from the inferior vena cava into the left atrium across a patent foramen ovale in a manner that resembles conditions in the fetal circulation.

Determinants of Myocardial Salvage During Acute Myocardial Infarction: Evaluation With a Combined Angiographic and CMR Myocardial Salvage Index

OBJECTIVES This study examined the contribution of symptom-to-reperfusion time, collateral flow, and antegrade flow in the infarct-related artery on myocardial salvage using a combined angiographic-cardiac magnetic resonance (CMR) method. BACKGROUND The myocardium supplied by an acutely occluded artery defines the anatomical area at risk for infarction. This area can be determined independently of residual coronary flow to the risk region. Moreover, the difference between this area and infarct size constitutes viable myocardium that has been salvaged. METHODS In 121 subjects presenting with ST-segment elevation myocardial infarction revascularized by primary percutaneous intervention, the angiographic anatomical area at risk was retrospectively measured using the Bypass Angioplasty Revascularization Investigation Myocardial Jeopardy Index (BARI score). Within 1 week, CMR was performed in the entire cohort and repeated in 89 subjects at 5 +/- 3 months to determine infarct size and wall motion recovery. The myocardial salvage index (MSI) was computed as (BARI score - infarct size)/left ventricular mass. RESULTS The MSI was negligible in patients with Thrombolysis In Myocardial Infarction (TIMI) flow grade < or =1, absent collateral vessels, and >4 h of symptom-to-reperfusion time, as compared with patients with TIMI flow grade >1 or existent collateral vessels (0.2 +/- 1.0 vs. 6.1 +/- 2.0, p < 0.001). The initial TIMI flow grade, time to reperfusion, presence of microvascular obstruction, and collateral flow were found to be independent predictors of MSI and infarct transmurality (p < 0.05 for both). The BARI score was only predictive of MSI (p < 0.001). The MSI correlated inversely with wall motion score at baseline (R = -0.27, p < 0.01) and at follow-up (R = -0.38, p < 0.001). Infarct transmurality also correlated with wall motion score at baseline (R = 0.52, p < 0.001) and at follow-up (R = 0.58, p < 0.001). Increasing MSI (p < 0.01) and decreasing infarct transmurality (p < 0.001) were associated with an improvement in wall motion and prognosis. CONCLUSIONS Early mechanical reperfusion and maintenance of antegrade or collateral flow independently preserves myocardial salvage primarily through a reduction in infarct transmurality. This novel integration of coronary angiography and CMR techniques to quantify myocardial salvage predicts functional recovery and improved prognosis.

Pulmonary Artery Balloon Counterpulsation for Right Ventricular Failure: II. Clinical Experience

The use of pulmonary artery balloon counterpulsation (PABC) provided immediate salvage following cardiac surgical procedures in 2 patients with biventricular failure in whom inotropic drugs and intraaortic balloon counterpulsation did not provide sufficient support to allow weaning from cardiopulmonary bypass. Although both patients eventually died, the hemodynamic effectiveness of PABC was documented. The various clinical settings for right ventricular as well as biventricular failure are reviewed, the currently available options for treatment are summarized, and the directions for future laboratory investigation and possible clinical applications are presented.