The Detection of Any Coronary Calcium Outperforms Framingham Risk Score as a First Step in Screening for Coronary Atherosclerosis

OBJECTIVE: The Framingham risk score is often recommended as the starting point for coronary disease screening. We compared the sensitivity of the Framingham risk score for moderate or greater degrees of atherosclerosis to the sensitivity achieved by simple observation of whether any coronary calcium is present. The reference standard was plaque burden as determined by coronary CT angiography.

METHODS: Of 1,416 men (mean age, 51.4 +/- 9.9 [SD] years) and 707 women (56.9 +/- 10.6 years), most were asymptomatic. Plaque burden (segment plaque score) and stenoses burden (Duke prognostic score) were estimated. A segment plaque score > 4 or a Duke prognostic score >3 indicated moderate or greater disease burden.

RESULTS: For a segment plaque score > 4, the presence of any calcium was 98% sensitive in men and 97% sensitive in women, whereas a Framingham risk score >10% was 74% sensitive in men and 36% sensitive in women. The negative likelihood ratio for the presence of calcium was 0.04 in subjects of either sex, whereas, for a Framingham risk score >3, calcium was 97% sensitive in men and 92% sensitive in women, whereas a Framingham risk score >10% was 88% sensitive in men and 35% sensitive in women. The negative likelihood ratio of calcium presence was 0.05 in men and 0.13 in women, whereas the negative likelihood ratio for a Framingham risk score

CONCLUSIONS: If subjects are excluded from further screening because they are in the Framingham low-risk category, almost two thirds of women and a quarter of men with substantial atherosclerosis will be missed. In contrast, the simple observation of any coronary calcium is highly sensitive and moderately specific.

PMID: 20410409

Pericardial Fat Burden on ECG-Gated Noncontrast CT in Asymptomatic Patients Who Subsequently Experience Adverse Cardiovascular Events

OBJECTIVES: We aimed to evaluate whether pericardial fat has value in predicting the risk of future adverse cardiovascular outcomes. Pericardial fat volume (PFV) and thoracic fat volume (TFV) can be routinely measured from noncontrast computed tomography (NCT) performed for calculating coronary calcium score (CCS) and may predict major adverse cardiac event (MACE) risk.

METHODS: From a registry of 2,751 asymptomatic patients without known cardiac artery disease and 4-year follow-up for MACE (cardiac death, myocardial infarction, stroke, late revascularization) after NCT, we compared 58 patients with MACE with 174 same-sex, event-free control subjects matched by a propensity score to account for age, risk factors, and CCS. The TFV was automatically calculated, and PFV was calculated with manual assistance in defining the pericardial contour, within which fat voxels were automatically identified. Independent relationships of PFV and TFV to MACE were evaluated using conditional multivariable logistic regression.

RESULTS: Patients experiencing MACE had higher mean PFV (101.8 +/- 49.2 cm(3) vs. 84.9 +/- 37.7 cm(3), p = 0.007) and TFV (204.7 +/- 90.3 cm(3) vs. 177 +/- 80.3 cm(3), p = 0.029) and higher frequencies of PFV >125 cm(3) (33% vs. 14%, p = 0.002) and TFV >250 cm(3) (31% vs. 17%, p = 0.025). After adjustment for Framingham risk score (FRS), CCS, and body mass index, PFV and TFV were significantly associated with MACE (odds ratio [OR]: 1.74, 95% confidence interval [CI]: 1.03 to 2.95 for each doubling of PFV; OR: 1.78, 95% CI: 1.01 to 3.14 for TFV). The area under the curve from receiver-operator characteristic analyses showed a trend of improved MACE prediction when PFV was added to FRS and CCS (0.73 vs. 0.68, p = 0.058). Addition of PFV, but not TFV, to FRS and CCS improved estimated specificity (0.72 vs. 0.66, p = 0.008) and overall accuracy (0.70 vs. 0.65, p = 0.009) in predicting MACE.

CONCLUSIONS: Asymptomatic patients who experience MACE exhibit greater PFV on pre-MACE NCT when they are compared with event-free control subjects with similar cardiovascular risk profiles. Our preliminary findings suggest that PFV may help improve prediction of MACE.

PMID: 20394896

Transthoracic and Transesophageal Echocardiography for the Indication of Suspected Infective Endocarditis: Vegetations, Blood Cultures and Imaging

OBJECTIVES: The aim of this study was to investigate the ability of transthoracic echocardiography (TTE) to detect vegetations and the relationship between blood cultures and transesophageal echocardiography (TEE).

METHODS: Five hundred eleven TTE and TEE pairs performed to evaluate endocarditis were retrospectively analyzed. Vegetation on TTE, prosthetic valve, change in regurgitation, and blood cultures were correlated with vegetation on TEE.

RESULTS: TTE detected 45% of vegetations seen on TEE. There was no difference for prosthetic valves. Prosthetic valves (odds ratio, 1.7; P = .03) and increased regurgitation (odds ratio, 1.7; P = .01) were associated with vegetations on TEE; staphylococcal bacteremia and fungemia were not. Negative blood cultures were associated with negative results on TEE (P < .0001), but 27% of patients with prosthetic valves had culture-negative endocarditis or nonbacterial thrombotic endocarditis, and 6% had abscesses missed by TTE.

CONCLUSIONS: This study demonstrates a limited capacity of TTE to detect vegetations. TEE may be an appropriate initial study to evaluate prosthetic valves. TEE for culture-negative endocarditis deserves further study.

PMID: 20138467

The Dynamic Nature of Coronary Artery Lesion Morphology Assessed By Serial Virtual Histology Intravascular Ultrasound Tissue Characterization

OBJECTIVES: We used virtual histology intravascular ultrasound (VH-IVUS) to investigate the natural history of coronary artery lesion morphology. Plaque stability is related to its histological composition.

METHODS: We performed serial (baseline and 12-month follow-up) VH-IVUS studies and examined 216 nonculprit lesions (plaque burden >40%) in 99 patients. Lesions were classified into pathological intimal thickening (PIT), VH-IVUS-derived thin-capped fibroatheroma (VH-TCFA), thick-capped fibroatheroma (ThCFA), fibrotic plaque, and fibrocalcific plaque.

RESULTS: At baseline, 20 lesions were VH-TCFAs; during follow-up, 15 (75%) VH-TCFAs “healed,” 13 became ThCFAs, 2 became fibrotic plaque, and 5 (25%) VH-TCFAs remained unchanged. Compared with VH-TCFAs that healed, VH-TCFAs that remained VH-TCFAs located more proximally (values are median [interquartile range]) (16 mm [15 to 18 mm] vs. 31 mm [22 to 47 mm], p = 0.013) and had larger lumen (9.1 mm(2) [8.2 to 10.7 mm(2)] vs. 6.9 mm(2) [6.0 to 8.2 mm(2)], p = 0.021), vessel (18.7 mm(2) [17.3 to 28.6 mm(2)] vs. 15.5 mm(2) [13.3 to 16.6 mm(2)]; p = 0.010), and plaque (9.7 mm(2) [9.6 to 15.7 mm(2)] vs. 8.4 mm(2) [7 to 9.7 mm(2)], p = 0.027) areas; however, baseline VH-IVUS plaque composition did not differ between VH-TCFAs that healed and VH-TCFAs that remained VH-TCFAs. Conversely, 12 new VH-TCFAs developed; 6 late-developing VH-TCFAs were PITs, and 6 were ThCFAs at baseline. In addition, plaque area at minimum lumen sites increased significantly in PITs (7.8 mm(2) [6.2 to 10.0 mm(2)] to 9.0 mm(2) [6.5 to 12.0 mm(2)], p < 0.001), VH-TCFAs (8.6 mm(2) [7.3 to 9.9 mm(2)] to 9.5 mm(2) [7.8 to 10.8 mm(2)], p = 0.024), and ThCFAs (8.6 mm(2) [6.8 to 10.2 mm(2)] to 8.8 mm(2) [7.1 to 11.4 mm(2)], p < 0.001) with a corresponding decrease lumen areas, but not in fibrous or fibrocalcific plaque.

CONCLUSIONS: Most VH-TCFAs healed during 12-month follow-up, whereas new VH-TCFAs also developed. PITs, VH-TCFAs, and ThCFAs showed significant plaque progression compared with fibrous and fibrocalcific plaque.

PMID: 20378076

Cost-Effectiveness of Coronary CT Angiography in Evaluation of Patients Without Symptoms Who Have Positive Stress Test Results

OBJECTIVE: Patients without symptoms who have positive stress test results are often referred for diagnostic catheter angiography in an evaluation for coronary artery disease (CAD). The purpose of this study was to use decision tree analysis to determine the cost-effectiveness and radiation dose that would result from performing coronary CT angiography (CTA) before catheterization.

METHODS: A decision tree was constructed to compare the false-negative rates, false-positive rates, costs, and radiation exposure of direct referral of patients for cardiac catheterization with the values associated with performing coronary CTA before catheterization. We assumed that patients referred for coronary CTA proceed to catheterization only when significant disease is identified. Costs for coronary CTA and diagnostic catheterization were obtained from the 2009 physician Medicare fee schedule. Sensitivity, specificity, and radiation dose were obtained by literature review.

RESULTS: Cost reduction with coronary CTA depends on the prevalence of coronary artery disease, but overall costs are reduced as long as the prevalence is less than 85%. At a 50% prevalence of coronary artery disease, performing coronary CTA before cardiac catheterization results in an average cost saving of $789 per patient with a false-negative rate of 2.5% and average additional radiation exposure of 1-2 mSv.

CONCLUSIONS: Performing coronary CTA before cardiac catheterization is a cost-effective strategy in the care of patients without symptoms who have positive stress test results when the probability that the patient has significant coronary artery disease is less than 50%. The false-negative rate with this strategy compares favorably with the false-negative rate of stress testing. The use of coronary CTA in this role can avoid many unnecessary cardiac catheterization procedures.

PMID: 20410412

Damage to the Esophagus After Atrial Fibrillation Ablation: Just the Tip of the Iceberg? High Prevalence of Mediastinal Changes Diagnosed by Endosonography

OBJECTIVES: Radiofrequency catheter ablation is increasingly used in the treatment of atrial fibrillation. Esophageal wall changes varying from erythema to ulcers have been described by endoscopy in up to 47% of patients following pulmonary vein isolation (PVI). Although esophageal changes are frequently reported, the development of a left atrial (LA)-esophageal fistula is fortunately rare. Nevertheless, mucosal changes may just represent “the tip of the iceberg.” The aim of this study was, therefore, to investigate the more subtle changes of and injuries to the posterior wall of the LA, the periesophageal and mediastinal connective tissue, and the whole wall of the esophagus, including mucosal changes by esophagogastroduodenoscopy (EGD) combined with radial endosonography (EUS).

METHODS: Twenty-nine patients (7 females; mean age, 57.7±10.5 years [range, 23–75 years]) underwent EGD and EUS before and after PVI within 48 hours. PVI was performed as a circumferential antral isolation of the septal and lateral pulmonary veins guided by a decapolar circular mapping catheter using a 3-dimensional mapping system with the integration of a preprocedurally acquired computed tomography scan of the left atrium. The maximum power applied was 30 W, with an open-irrigated catheter using a maximum flow rate of 30 mL/min. In all patients, the esophagus was reconstructed using the same computed tomography scan and displayed during the ablation procedure. In case of newly detected periesophageal changes, EGD and EUS were repeated 1 week after the PVI. In all patients, a regular contact area between the LA and the esophagus could be demonstrated before PVI.

RESULTS: The mean vertical contact length was 4.4±1.5 cm (range, 2–10 cm); and the mean distance between the anterior wall of the esophagus and the endocardium was 2.6±0.8 mm (range, 1.4–4.0 mm). After PVI, morphological changes of the periesophageal connective tissue and the posterior wall of the LA were diagnosed by endosonography in 8 patients (27%; 95% confidence interval, 12.73–47.24). No mucosal changes of the esophagus in terms of erythema or ulcers were found. In all but one patient (who refused the control), all periesophageal and atrial changes had resolved within 1 week. No atrioesophageal fistula occurred during follow-up (mean follow-up, 294±110 days [range, 36–431 days]).

CONCLUSIONS: Mucosal changes of the esophagus after PVI-like ulcers or erythema could not be demonstrated, yet structural changes of the mediastinum, which were only visible by endosonography, occurred in 27% of patients in the present study. This may indicate a higher than expected periesophageal injury because of PV ablation. Endosonography might prove to be a sensitive and reliable tool in the follow-up after PVI

PMID: 20194799

Thoracic Aorta: Prospective Electrocardiographically Triggered CT Angiography With Dual-Source CT-Feasibility, Image Quality, and Dose Reduction

OBJECTIVES: To prospectively investigate the feasibility, image quality, and radiation dose for prospective electrocardiographically (ECG) triggered sequential dual-source computed tomographic (CT) angiography of the thoracic aorta in comparison to retrospective ECG-gated helical dual-source CT angiography.

METHODS: This study was approved by the institutional review board; informed consent was obtained. One hundred thirty-nine patients referred for ECG-assisted dual-source CT angiography of the thoracic aorta were prospectively enrolled. Inclusion criteria were stable sinus rhythm and heart rate of 80 beats per minute or less. Tube voltage was adjusted to body mass index (< 25.0 kg/m(2), 100 kV, n = 58; > 25.0 kg/m(2), 120 kV, n = 81). In both cohorts, patients were randomly assigned to prospective or retrospective ECG-assisted data acquisition. In both groups, tube current (250 mAs per rotation) was centered at 70% of the R-R cycle. The presence of motion or stair-step artifacts of the thoracic aorta was independently assessed by two readers. Effective radiation dose was calculated from the dose-length product.

RESULTS: Subjective scoring of motion and stair-step artifacts was equivalent for both techniques. Scan length was not significantly different (23.8 cm +/- 2.4 [standard deviation] vs 23.7 cm +/- 2.5 for prospective and retrospective ECG-triggered CT angiography, respectively; P = .54). Scanning time was significantly longer for prospective ECG-triggered CT angiography (18.8 seconds +/- 3.4 vs 16.4 seconds +/- 3.3, P < .001). Mean estimated effective dose was significantly lower for prospective data acquisition (100 kV, 1.9 mSv +/- 0.5 vs 4.1 mSv +/- 0.7, P < .001; 120 kV, 5.3 mSv +/- 1.1 vs 9.5 mSv +/- 3.0, P < .001).

CONCLUSION: Prospective ECG-gated sequential dual-source CT angiography of the thoracic aorta is feasible, despite the slightly longer acquisition time. Thus, motion-free imaging of the thoracic aorta is possible at significantly lower radiation exposure than retrospective ECG-gated helical dual-source CT angiography in certain patients with a regular heart rate.

PMID: 20160003

Composition of Carotid Atherosclerotic Plaque Is Associated With Cardiovascular Outcome: A Prognostic Study

OBJECTIVES: Identification of patients at risk for primary and secondary manifestations of atherosclerotic disease progression is based mainly on established risk factors. The atherosclerotic plaque composition is thought to be an important determinant of acute cardiovascular events, but no prospective studies have been performed. The objective of the present study was to investigate whether atherosclerotic plaque composition is associated with the occurrence of future vascular events.

METHODS: Atherosclerotic carotid lesions were collected from patients who underwent carotid endarterectomy and were subjected to histological examination. Patients underwent clinical follow-up yearly, up to 3 years after carotid endarterectomy. The primary outcome was defined as the composite of a vascular event (vascular death, nonfatal stroke, nonfatal myocardial infarction) and vascular intervention. The cumulative event rate at 1-, 2-, and 3-year follow-up was expressed by Kaplan–Meier estimates, and Cox proportional hazards regression analyses were performed to assess the independence of histological characteristics from general cardiovascular risk factors.

RESULTS: During a mean follow-up of 2.3 years, 196 of 818 patients (24%) reached the primary outcome. Patients whose excised carotid plaque revealed plaque hemorrhage or marked intraplaque vessel formation demonstrated an increased risk of primary outcome (risk difference=30.6% versus 17.2%; hazard ratio [HR] with [95% confidence interval]=1.7 [1.2 to 2.5]; and risk difference=30.0% versus 23.8%; HR=1.4 [1.1 to 1.9], respectively). Macrophage infiltration (HR=1.1 [0.8 to 1.5]), large lipid core (HR=1.1 [0.7 to 1.6]), calcifications (HR=1.1 [0.8 to 1.5]), collagen (HR=0.9 [0.7 to 1.3]), and smooth muscle cell infiltration (HR=1.3 [0.9 to 1.8]) were not associated with clinical outcome. Local plaque hemorrhage and increased intraplaque vessel formation were independently related to clinical outcome and were independent of clinical risk factors and medication use.

CONCLUSIONS: The local atherosclerotic plaque composition in patients undergoing carotid endarterectomy is an independent predictor of futurecardiovascular events.

PMID:

Extracardiac Findings on Cardiac Computed Tomography: A Radiologist’s Perspective

There has been debate in the cardiology literature as to how to handle unexpected noncardiac findings on cardiac computed tomography examinations. From the perspective of a radiologist, all structures on the presented images should be assessed. The interpreter needs to carefully window the findings down to potentially important ones. Then the question becomes what to do next. Cardiologists who take primary responsibility for cardiac computed tomography examinations must be able to recognize noncardiac findings that require immediate action. Although infrequent, their clinical impact can be substantial. False-positive results will occur; minimizing these depends on knowledge of common trivial findings, normal variants, and customary workup and follow-up recommendations. This implies experience in interpreting structures outside the heart. Therefore, help from an experienced and decisive radiologist should maximize sensitivity for significant lesions while minimizing the number of false-positive diagnoses.

PMID: 20378072

Microvascular Obstruction: Underlying Pathophysiology and Clinical Diagnosis

Successful restoration of epicardial coronary artery patency after prolonged occlusion might result in microvascular obstruction (MVO) and is observed both experimentally as well as clinically. In reperfused myocardium, myocytes appear edematous and swollen from osmotic overload. Endothelial cell changes usually accompany the alterations seen in myocytes but lag behind myocardial cell injury. Endothelial cells become voluminous, with large intraluminal endothelial protrusions into the vascular lumen, and together with swollen surrounding myocytes occlude capillaries. The infiltration and activation of neutrophils and platelets and the deposition of fibrin also play an important role in reperfusion-induced microvascular damage and obstruction. In addition to these ischemia-reperfusion-related events, coronary microembolization of atherosclerotic debris after percutaneous coronary intervention is responsible for a substantial part of clinically observed MVO. Microvascular flow after reperfusion is spatially and temporally complex. Regions of hyperemia, impaired vasodilatory flow reserve and very low flow coexist and these perfusion patterns vary over time as a result of reperfusion injury. The MVO first appears centrally in the infarct core extending toward the epicardium over time. Accurate detection of MVO is crucial, because it is independently associated with adverse ventricular remodeling and patient prognosis. Several techniques (coronary angiography, myocardial contrast echocardiography, cardiovascular magnetic resonance imaging, electrocardiography) measuring slightly different biological and functional parameters are used clinically and experimentally. Currently there is no consensus as to how and when MVO should be evaluated after acute myocardial infarction.

PMID:

Feasibility of FDG Imaging of the Coronary Arteries: Comparison Between Acute Coronary Syndrome and Stable Angina

OBJECTIVES: This study tested the hypothesis that fluorodeoxyglucose (FDG) uptake within the ascending aorta and left main coronary artery (LM), measured using positron emission tomography (PET), is greater in patients with recent acute coronary syndrome (ACS) than in patients with stable angina. Inflammation is known to play an important role in atherosclerosis. Positron emission tomography imaging with ¹⁸F-FDG provides a measure of plaque inflammation.

METHODS: Twenty-five patients (mean age 57.9 ± 9.8 years, 72% male, 10 ACS, and 15 stable angina) underwent cardiac computed tomographic angiography and PET imaging with ¹⁸F-FDG after invasive angiography. Images were coregistered, and FDG uptake was measured at locations of interest for calculation of target-to-background ratios (TBR). Additionally, FDG uptake was measured at the site of the lesion deemed clinically responsible for the presenting syndrome (culprit) by virtue of locating the stent deployed to treat the syndrome.

RESULTS: The FDG uptake was higher in the ACS versus the stable angina groups in the ascending aorta (median [interquartile ranges] TBR 3.30 [2.69 to 4.12] vs. 2.43 [2.00 to 2.86], p = 0.02), as well as the LM (2.48 [2.30 to 2.93] vs. 2.00 [1.71 to 2.44], p = 0.03, respectively). The TBR was greater for culprit lesions associated with ACS than for lesions stented for stable coronary syndromes (2.61 vs. 1.74, p = 0.02). Furthermore, the TBR in the stented lesions (in ACS and stable angina groups) correlated with C-reactive protein (r = 0.58, p = 0.04).

CONCLUSIONS: This study shows that in patients with recent ACS, FDG accumulation is increased both within the culprit lesion as well as in the ascending aorta and LM. This observation suggests inflammatory activity within atherosclerotic plaques in acute coronary syndromes and supports intensification of efforts to refine PET methods for molecular imaging of coronary plaques.

PMID: http://imaging.onlinejacc.org/cgi/content/abstract/3/4/388

Transcatheter Valve-in-Valve Implantation for Failed Bioprosthetic Heart Valves

OBJECTIVES: The majority of prosthetic heart valves currently implanted are tissue valves that can be expected to degenerate with time and eventually fail. Repeat cardiac surgery to replace these valves is associated with significant morbidity and mortality. Transcatheter heart valve implantation within a failed bioprosthesis, a “valve-in-valve” procedure, may offer a less invasive alternative.

METHODS: Valve-in-valve implantations were performed in 24 high-risk patients.

RESULTS: Failed valves were aortic (n=10), mitral (n=7), pulmonary (n=6), or tricuspid (n=1) bioprostheses. Implantation was successful with immediate restoration of satisfactory valve function in all but 1 patient. No patient had more than mild regurgitation after implantation. No patients died during the procedure. Thirty-day mortality was 4.2%. Mortality was related primarily to learning-curve issues early in this high-risk experience. At baseline, 88% of patients were in New York Heart Association functional class III or IV; at the last follow-up, 88% of patients were in class I or II. At a median follow-up of 135 days (interquartile range, 46 to 254 days) and a maximum follow-up of 1045 days, 91.7% of patients remained alive with satisfactory valve function.

CONCLUSIONS: Transcatheter valve-in-valve implantation is a reproducible option for the management of bioprosthetic valve failure. Aortic, pulmonary, mitral, and tricuspid tissue valves were amenable to this approach. This finding may have important implications with regard to valve replacement in high-risk patients.

PMID:

Prevalence of Asymptomatic Coronary Artery Disease in Ischemic Stroke Patients. The PRECORIS Study.

BACKGROUND: -Coronary artery disease (CAD) is a significant cause of morbidity and mortality in stroke patients. Some patients with asymptomatic CAD might benefit from specific prevention, but the prevalence of asymptomatic CAD is not well known. We assessed the prevalence of >/=50% asymptomatic CAD in patients with ischemic stroke or transient ischemic attack and whether the prevalence is related to traditional vascular risk factors and cervicocephalic atherosclerosis. Methods and Results-From January 2006 to February 2009, consecutive patients between 45 and 75 years of age with nondisabling, noncardioembolic ischemic stroke or transient ischemic attack and no prior history of CAD were enrolled in the study. All patients had a 64-section computed tomography coronary angiography and a detailed cervicocephalic arterial workup. Risk factors were assessed individually and through the Framingham Risk Score. Among 300 patients included in the study, 274 had computed tomography coronary angiography. The prevalence of >/=50% asymptomatic CAD was 18% (95% confidence interval [CI], 14 to 23; n=50). Asymptomatic CAD was independently associated with traditional risk factors assessed individually and through the Framingham Risk Score (odds ratio [OR], 2.6; 95% CI, 1.0 to 7.6 for a 10-year risk of coronary heart disease of 10% to 19%; and OR, 7.3; 95% CI, 2.8 to 19.1 for a 10 year-risk of coronary heart disease >/=20%), the presence of at least 1 >/=50% cervicocephalic artery stenosis (OR, 4.0; 95% CI, 1.4 to 11.2), excessive alcohol consumption (OR, 3.1; 95% CI 1.3 to 7.3), and ankle brachial index <0.9 (OR, 2.2; 95% CI, 0.9 to 5.2). The prevalence of >/=50% asymptomatic CAD was also related to the extent of cervicocephalic atherosclerosis. Conclusions-About one fifth of patients with nondisabling, noncardioembolic ischemic stroke or transient ischemic attack have >/=50% asymptomatic CAD. In addition to vascular risk factors, the presence of >/=50% cervicocephalic artery stenosis is strongly related to >/=50% asymptomatic CAD.

PMID: 20351236

Locating the Right Phrenic Nerve by Imaging the Right Pericardiophrenic Artery With Computerized Tomographic Angiography: Implications for Balloon Based Procedures

OBJECTIVES: Phrenic nerve (PN) injury, a known complication from radiofrequency (RF) catheter ablation of atrial fibrillation (AF), has been more commonly reported with balloon based pulmonary vein isolation. We present a novel approach to locating the PN and predicting patients at higher risk of this complication.

METHODS: The study included 2 groups of patients. In the first group of 71 patients, computerized tomographic angiography (CTA) with 3-D reconstruction of the left atrium (LA) was obtained prior to an RF ablation procedure. The location of the right pericardiophrenic artery (RPA) was identified on the axial CTA images and the artery distance to the right superior pulmonary vein (RSPV) ostium was measured in the 3-D image. During ablation, the location of the right PN was identified by pacing maneuvers. The distance to the ostium of the RSPV was measured by venography and compared to the CTA artery measurement. In the second group, CTA imaging from 37 subjects who were enrolled in 3 investigational balloon ablation trials were analyzed using the same PN location technique and compared against the clinical outcomes. In this analysis, the CTA segmentation and PN location was performed in a blinded fashion as to any clinical evidence of PN injury.

RESULTS: The mean measurement difference between PN capture and imaged RPA was 0.8 mm (p=0.539). In all cases, the imaged RPA could reliably identify the approximate location of the right PN (R-square 0.984, p <0.001). Moreover, this analysis suggests that a PN location within 10 mm of the RSPV poses a higher risk of PN injury using these balloon ablation devices.

CONCLUSIONS: Imaging the right pericardiophrenic artery can reliably locate the right phrenic nerve. This technique might identify anatomy more vulnerable to phrenic nerve injury using balloon based ablation systems.

PMID: 20348030

Cardiac MRI in Pulmonary Artery Hypertension: Correlations Between Morphological and Functional Parameters and Invasive Measurements

OBJECTIVES: To compare cardiac MRI with right heart catheterisation in patients with pulmonary hypertension (PH) and to evaluate its ability to assess PH severity.

METHODS: Forty patients were included. MRI included cine and phase-contrast sequences, study of ventricular function, cardiac cavity areas and ratios, position of the interventricular septum (IVS) in systole and diastole, and flow measurements. We defined four groups according to the severity of PH and three groups according to IVS position: A, normal position; B, abnormal in diastole; C, abnormal in diastole and systole.

RESULTS: IVS position was correlated with pulmonary artery pressures and PVR (pulmonary vascular resistance). Median pulmonary artery pressures and resistance were significantly higher in patients with an abnormal septal position compared with those with a normal position. Correlations were good between the right ventricular ejection fraction and PVR, right ventricular end-systolic volume and PAP, percentage of right ventricular area change and PVR, and diastolic and systolic ventricular area ratio and PVR. These parameters were significantly associated with PH severity.

CONCLUSIONS: Cardiac MRI can help to assess the severity of PH.

PMID: 20094890