Right Ventricular Injury in ST-Elevation Myocardial Infarction: Risk Stratification by Visualization of Wall Motion, Edema and Delayed Enhancement Cardiac Magnetic Resonance

OBJECTIVES: Patients with right ventricular injury (RVI) complicating ST-elevation myocardial infarction (STEMI) suffer from impaired prognosis, but it is unclear which patients are at risk of developing RVI. Cardiac magnetic resonance (CMR) can identify these patients and might add important information on risk stratification, prognosis and treatment. Aims were to determine the predictors and the prognostic significance of RVI assessed by wall motion abnormalities, edema, myocardial-salvage-index (MSI) and delayed enhancement (DE) in acute reperfused STEMI.

METHODS: We studied 450 patients 1-4 days after primary angioplasty in STEMI. T2-weighted and DE CMR was used for visualizing edema and scar to calculate MSI. Cine-imaging was performed to assess wall motion abnormalities, which, in combination with edema, were considered diagnostic for RVI. Patients with RVI were compared to matched patients with isolated left ventricular (LV) infarction. The primary endpoint was the occurrence of a major adverse cardiac event (MACE): a composite of death, reinfarction and congestive heart failure after a median follow-up period of 20.9 months.

RESULTS: RVI was present in 69 patients and 41/69 showed myocardial necrosis. In a multivariable stepwise forward logistic regression analysis a high RV myocardial mass (Odds-Ratio 2.06, 95% Confidence-Interval 1.18-3.58, p=0.012) and a low TIMI-flow pre angioplasty (Odds-Ratio 0.50, 95% CI 0.32-0.76, p=0.011) were associated with RVI. Cox regression analysis revealed RVI as the most statistically significant predictor of time to MACE (Hazard-Ratio 3.36, 95% CI 1.99-5.66, p

CONCLUSIONS: RVI detected by CMR is a strong and independent predictor of clinical outcome after acute reperfused STEMI.

PMID:

2011 ACCF/AHA Guideline for the Diagnosis and Treatment of Hypertrophic Cardiomyopathy: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines

Practice guidelines are developed through a rigorous methodological approach  that mandates the review and consideration of the available medical literature.  Practice guidelines define the role of specific diagnostic and therapeutic  modalities, including noninvasive and invasive procedures, in the diagnosis and  management of patients with various cardiovascular diseases. These  evidence-based guidelines are intended to assist physicians in clinical decision making by describing a range of generally acceptable approaches for the diagnosis, management, or prevention of specific diseases or conditions. They attempt to define practices that meet the needs of most patients in most circumstances by categorizing the recommendations into a classification system. The development of practice guidelines are the domain of the ACCF/AHA Task Force on Practice Guidelines and are published in JACC and Circulation.

PMID: 22068435

Comparison of Severity of Aortic Regurgitation by Cardiovascular Magnetic Resonance Versus Transthoracic Echocardiography

OBJECTIVES: Transthoracic echocardiography is the current standard for assessing aortic regurgitation (AR).  AR severity can also be evaluated by flow measurement in the ascending aorta using cardiac magnetic resonance (CMR); however, the optimal site for flow measurement and the regurgitant fraction (RF) severity grading criteria that best compares with the transthoracic echocardiographic assessment of AR are not clear.  The present study aimed to determine the optimal site and RF grading criteria for AR severity using phase-contrast flow measurements and CMR.

METHODS: A prospective observational study was performed of 107 consecutive patients who were undergoing CMR of the thoracic aorta.  Using CMR, the AR severity and aortic dimensions were measured at 3 levels in the aorta (the sinotubular junction, mid-ascending aorta, and distal ascending aorta).

RESULTS: The results were compared to the transthoracic echocardiographic grade of AR severity using multiple qualitative and quantitative criteria (grade 0, none; I+, mild; II+, mild to moderate; III+, moderate to severe; and IV+, severe).  The mean RF values were significantly greater at the sinotubular junction than at the distal ascending aorta (13 ± 13.3% vs 9.4 ± 12.6%, respectively; p <0.001).  The RF values that best defined AR severity using phase-contrast CMR were as follows: grade 0 to I+, <8%; grade II+, 8% to 19%; grade III+, 20 to 29%; and grade IV+, 30%) at the sinotubular or mid-ascending aorta.

CONCLUSIONS: In conclusion, the quantitative RF values of AR severity using phase-contrast flow are best assessed in the proximal ascending aorta and differ from recognized quantitative echocardiographic criteria.

PMID: 21784393

Left Ventricular Structural Remodeling in Health and Disease: With Special Emphasis on Volume, Mass, and Geometry

The changes in left ventricular (LV) structure and geometry that evolve after myocardial injury or overload usually involve chamber dilation and/or hypertrophy. Such architectural remodeling can be classified as eccentric or concentric. Consideration of LV volume, mass, and relative wall thickness (or mass/volume) allows classification of LV remodeling that includes virtually all LV remodeling changes that are seen in health and disease. These various architectural changes generally include the development of LV hypertrophy in a pattern that is closely related to the type of injury or overload, and they are accompanied by differences in cardiac function and hemodynamics. Some patterns of remodeling are associated with adverse outcomes whereas others appear to be adaptive and physiologic without adverse consequences. Considering all patients with LV hypertrophy as a homogenous group is inconsistent with our understanding of the various remodeling patterns that are discussed in this review.

PMID: 21996383

Multimodality Imaging in Transcatheter Aortic Valve Implantation and Post-Procedural Aortic Regurgitation: Comparison Among Cardiovascular Magnetic Resonance, Cardiac Computed Tomography, and Echocardiography

OBJECTIVES: The purpose of this study was to determine imaging predictors of aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) and the agreement and reproducibility of cardiovascular magnetic resonance (CMR), cardiac computed tomography (CCT), and transthoracic echocardiography (TTE) in aortic root assessment. The optimal imaging strategy for planning TAVI is unclear with a paucity of comparative multimodality imaging data. The association between aortic root morphology and outcomes after TAVI also remains incompletely understood.

METHODS: A total of 202 consecutive patients assessed by CMR, CCT, and TTE for TAVI were studied. Agreement and variability among and within imaging modalities was assessed by Bland-Altman analysis. Postoperative AR was assessed by TTE.

RESULTS: Of the 202 patients undergoing TAVI assessment with both CMR and TTE, 133 also underwent CCT. Close agreement was observed between CMR and CCT in dimensions of the aortic annulus (bias, –0.4 mm; 95% limits of agreement: –5.7 to 5.0 mm), and similarly for sinus of Valsalva, sinotubular junction, and ascending aortic measures. Agreement between TTE-derived measures and either CMR or CCT was less precise. Intraobserver and interobserver variability were lowest with CMR. The presence and severity of AR after TAVI were associated with larger aortic valve annulus measurements by both CMR (p = 0.03) and CCT (p = 0.04) but not TTE-derived measures (p = 0.10). Neither CCT nor CMR measures of annulus eccentricity, however, predicted AR after TAVI (p = 0.33 and p = 0.78, respectively).

CONCLUSIONS: In patients undergoing imaging assessment for TAVI, the presence and severity of AR after TAVI were associated with larger aortic annulus measurements by both CMR and CCT, but not TTE. Both CMR and CCT provide highly reproducible information in the assessment of patients undergoing TAVI.

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Cardiac Magnetic Resonance Imaging Pericardial Late Gadolinium Enhancement and Elevated Inflammatory Markers Can Predict the Reversibility of Constrictive Pericarditis After Antiinflammatory Medical Therapy

OBJECTIVES: Constrictive pericarditis (CP) is a disabling disease, and usually requires pericardiectomy to relieve heart failure. Reversible CP has been described, but there is no known method to predict the reversibility. Pericardial inflammation may be a marker for reversibility. As a pilot study, we assessed whether cardiac magnetic resonance imaging pericardial late gadolinium enhancement (LGE) and inflammatory biomarkers could predict the reversibility of CP after anti-inflammatory therapy.

METHODS: Twenty-nine CP patients received anti-inflammatory medications after cardiac magnetic resonance imaging. Fourteen patients had resolution of CP, whereas 15 patients had persistent CP after 13 months of follow-up. Baseline LGE pericardial thickness was greater in the group with reversible CP than in the persistent CP group (4±1 versus 2±1 mm, P=0.001). Qualitative intensity of pericardial LGE was moderate or severe in 93% of the group with reversible CP and in 33% of the persistent CP group (P=0.002).

RESULTS: Cardiac magnetic resonance imaging LGE pericardial thickness ≥3 mm had 86% sensitivity and 80% specificity to predict CP reversibility. The group with reversible CP also had higher baseline C-reactive protein and erythrocyte sedimentation rate than the persistent CP group (59±52 versus 12±14 mg/L, P=0.04 and 49±25 versus 15±16 mm/h, P=0.04, respectively). Anti-inflammatory therapy was associated with a reduction in C-reactive protein, erythrocyte sedimentation rate, and pericardial LGE in the group with reversible CP but not in the persistent CP group.

CONCLUSIONS: Reversible CP was associated with pericardial and systemic inflammation. Anti-inflammatory therapy was associated with a reduction in pericardial and systemic inflammation and LGE pericardial thickness, with resolution of CP physiology and symptoms. Further studies in a larger number of patients are needed.

PMID: 21969014

Timing of Cardiovascular MR Imaging After Acute Myocardial Infarction: Effect on Estimates of Infarct Characteristics and Prediction of Late Ventricular Remodeling

OBJECTIVES: To define the evolution of infarct characteristics with cardiovascular magnetic resonance (MR) imaging and to assess which of the cardiovascular MR data acquired at day 2 or at 1 week after acute myocardial infarction (AMI), is the stronger predictor of infarct size and left ventricular (LV) function measured at 3 months.

METHODS: The study protocol was reviewed and approved by the local research ethics committee, and written informed consent was obtained. Forty-eight patients with reperfused AMI underwent cine, T2-weighted, and late gadolinium enhancement cardiovascular MR imaging at days 2, 7, 30, and 90 after index presentation. Continuous data between times were compared by using paired t tests or one-way analysis of variance. Multiple linear regression analyses were used to predict linear end points.

RESULTS: Infarct size and extent of myocardial edema decreased significantly between day 2 and 1 week: Mean scar as a percentage of LV mass and standard deviation (SD), respectively, were 27.2 and 13.9 versus 21.6 and 14.1 (P < .001), and myocardial edema as a percentage of LV mass and SD, respectively, were 37.9 and 15.2 versus 32.3 and 14.3 (P = .003). These changes were accompanied by a significant improvement in LV ejection fraction (LVEF): Mean percentage of LVEF and SD, respectively, were 41.7 and 9.6 versus 44.6 and 10.1 (P < .001). When comparing data acquired at day 2 and 1 week, only cardiovascular MR data acquired at 1 week were independent predictors of LVEF and infarct size at 3 months.

CONCLUSIONS: LVEF, infarct size, and extent of myocardial edema changed significantly during the 1st week after AMI. Overall, cardiovascular MR measurements acquired after 1 week have greater predictive value for infarct size and LV function at 3 months than data acquired at day 2.

PMID: 21828188

Long-Term Prognostic Value of Myocardial Salvage Assessed by Cardiovascular Magnetic Resonance in Acute Reperfused Myocardial Infarction

OBJECTIVES: In acute myocardial infarction, cardiovascular magnetic resonance (CMR) allows for quantifying the extent of salvaged myocardium after reperfusion as a potential strong end point for clinical trials. The aim of this study was to investigate whether the early prognostic significance of myocardial salvage assessed by CMR is sustained at long-term clinical follow-up in patients with ST-elevation myocardial infarction (STEMI) undergoing primary angioplasty.

METHODS: analysed 208 consecutive patients with STEMI undergoing primary angioplasty

RESULTS: The median MSI was 48 (IQR 27 to 73). Long-term follow-up was available in 202 patients (97%) at a median of 18.5 months (IQR 13.8 to 20.8). Major adverse cardiovascular events occurred in 33 patients (16%), with a significantly lower event rate in the MSI ≥ median group (7 vs 26 events, p

CONCLUSIONS: MSI assessed by CMR predicts long-term clinical outcome in acute reperfused STEMI. Therefore, our data support the use of myocardial salvage as an end point for clinical trials investigating novel reperfusion strategies.

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Performance of Angiographic, Electrocardiographic and MRI Methods to Assess the Area at Risk in Acute Myocardial Infarction

OBJECTIVES: Validation of methods to assess the area at risk (AAR) in patients with ST elevation myocardial infarction is limited. A study was undertaken to test different AAR methods using established physiological concepts to provide a reference standard. Main outcome measuredIn 78 reperfused patients with first ST elevation myocardial infarction, AAR was measured by electrocardiographic (Aldrich), angiographic (Bypass Angioplasty Revascularization Investigation (BARI), APPROACH) and cardiovascular magnetic resonance methods (T2-weighted hyperintensity and delayed enhanced endocardial surface area (ESA)). The following established physiological concepts were used to evaluate the AAR

METHODS: (1) AAR size is always ≥ infarct size (IS); (2) in transmural infarcts AAR size=IS; (3) correlation between AAR size and IS increases as infarct transmurality increases; and (4) myocardial salvage ((AAR-IS)/AAR×100) is inversely related to infarct transmurality.

RESULTS: Overall, 65%, 87%, 76%, 87% and 97% of patients using the Aldrich, BARI, APPROACH, T2-weighted hyperintensity and ESA methods obeyed the concept that AAR size is ≥IS. In patients with transmural infarcts (n=22), Bland-Altman analysis showed poor agreement (wide 95% limits of agreement) between AAR size and IS for the BARI, Aldrich and APPROACH methods (95% CI -22.9 to 29.6, 95% CI -28.3 to 21.3 and 95% CI -16.9 to 20.0, respectively) and better agreement for T2-weighted hyperintensity and ESA (95% CI -6.9 to 16.6 and 95% CI -4.3 to 18.0, respectively). Increasing correlation between AAR size and IS with increasing infarct transmurality was observed for the APPROACH, T2-weighted hyperintensity and ESA methods, with ESA having the highest correlation (r=0.93, p

CONCLUSIONS: For measuring AAR, cardiovascular magnetic resonance methods are better than angiographic methods, which are better than electrocardiographic methods. Overall, ESA performed best for measuring AAR in vivo.

PMID: 21930725

Non-Invasive Estimation of Pulmonary Vascular Resistance With Cardiac Magnetic Resonance

OBJECTIVES: To develop a cardiac magnetic resonance (CMR) method for non-invasive estimation of pulmonary vascular resistance (PVR).

METHODS: The study comprised 100 consecutive patients with known or suspected pulmonary hypertension (PH; 53 ± 16 years, 73% women) who underwent same-day right heart catheterization (RHC) and CMR. Increased PVR was defined from RHC as >3 WU (n = 66, 66%). From CMR cine and phase-contrast images, right ventricular (RV) volumes and ejection fraction (RVEF), pulmonary artery (PA) flow velocities and areas, and cardiac output were quantified. The best statistical model to estimate PVR was obtained from a derivation cohort (n = 80) based on physiological plausibility and statistical criteria. Validity of the model was assessed in the remaining 20 patients (validation cohort).

RESULTS: The CMR-derived model was: estimated PVR (in WU) = 19.38 – [4.62 × Ln PA average velocity (in cm/s)] – [0.08 × RVEF (in %)]. In the validation cohort, the correlation between invasively quantified and CMR-estimated PVR was 0.84 (P < 0.001). The mean bias between the RHC-derived and CMR-estimated PVR was -0.54 (agreement interval -6.02 to 4.94 WU). The CMR model correctly classified 18 (90%) of patients as having normal or increased PVR (area under the receiver operator characteristics curve 0.97; 95% confidence interval: 0.89-1.00).

CONCLUSIONS: Non-invasive estimation of PVR using CMR is feasible and may be valuable for PH diagnosis and/or follow-up.

PMID: 21624902

Scar Size and Characteristics Assessed by CMR Predict Ventricular Arrhythmias in Ischaemic Cardiomyopathy: Comparison of Previously Validated Models

OBJECTIVES: Sudden cardiac death is a major cause of mortality in patients with ischaemic cardiomyopathy. Risk stratification remains challenging. Currently, there is growing interest in scar characteristic assessment as a predictor of sudden cardiac death using cardiac magnetic resonance imaging (CMR). Standard analysis methods are lacking. The present study evaluated previously validated methods of scar assessment by CMR with late gadolinium enhancement (LGE) in their ability to predict ventricular tachyarrhythmias.

METHODS: Patients with ischaemic cardiomyopathy who received an implantable cardioverter defibrillator for primary prevention and in whom a LGE–CMR was performed, were included. Scar core size, peri-infarct zone and total scar size, which is defined as the sum of the core size and peri-infarct zone, were assessed using three previously validated models, and their ability to predict ventricular tachyarrhythmias was evaluated.

RESULTS: Fifty-five patients were included (mean age 64.6±10.8 years, 43 men). During a median follow-up of 2.0 years (IQR 1.0–3.0 years) 26% of patients reached the endpoint of ventricular tachyarrhythmia. All scar characteristics (ie, total scar size, scar core size and peri-infarct zone) of the three methods were predictors of the endpoint (p

CONCLUSIONS: LGE–CMR-derived scar tissue characteristics are of predictive value for the occurrence of ventricular tachyarrhythmias in patients with ischaemic cardiomyopathy. Additional estimation of scar core size and/or peri-infarct zone does not appear to increase the diagnostic accuracy over total scar size alone.

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Right Ventriculo-Arterial Coupling In Pulmonary Hypertension: A Magnetic Resonance Study

OBJECTIVES: To quantify right ventriculo-arterial coupling in pulmonary hypertension by combining standard right heart catheterisation (RHC) and cardiac magnetic resonance (CMR) and to estimate it non-invasively with CMR alone.

METHODS: This was a cross-sectional analysis in a retrospective cohort of consecutive patients from a tertiary care centre. There were 139 adults referred for pulmonary hypertension evaluation. Interventions: CMR and RHC within 2 days (n=151 test pairs). The main outcome measures right ventriculo-arterial coupling was quantified as the ratio of pulmonary artery (PA) effective elastance (Ea, index of arterial load) to right ventricular maximal end-systolic elastance (Emax, index of contractility). Right ventricular end-systolic volume (ESV) and stroke volume (SV) were obtained from CMR and adjusted to body surface area. RHC provided mean PA pressure (mPAP) as a surrogate of right ventricular end-systolic pressure, pulmonary capillary wedge pressure (PCWP) and pulmonary vascular resistance index (PVRI). Ea was calculated as (mPAP − PCWP)/SV and Emax as mPAP/ESV.

RESULTS: Ea increased linearly with advancing severity as defined by PVRI quartiles (0.19, 0.50, 0.93 and 1.63 mmHg/ml/m2, respectively; p

CONCLUSIONS: Right ventriculo-arterial coupling in pulmonary hypertension can be studied with standard RHC and CMR. Arterial load increases with disease severity whereas contractility cannot progress in parallel, leading to severe uncoupling.

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Prognostic Value of Routine Cardiac Magnetic Resonance Assessment of Left Ventricular Ejection Fraction and Myocardial Damage: An International, Multicenter Study

OBJECTIVES: Cardiac Magnetic Resonance (CMR) is considered the reference standard for assessment of left ventricular ejection fraction (LVEF) and myocardial damage. However, few studies have evaluated the relationship between CMR findings and patient outcome, and of these most are small and none are multicenter. We performed an international, multicenter study to assess the prognostic importance of routine CMR in patients with known or suspected heart disease.

METHODS: Consecutive patients from 10 centers in 6 countries undergoing routine CMR assessment of LVEF and myocardial damage by cine and delayed-enhancement imaging (DE-CMR), respectively, were screened for enrollment. Clinical data, CMR protocol information and findings were collected at all sites and submitted to the data-coordinating center for verification of completeness and analysis. The primary endpoint was all-cause mortality.

RESULTS: A total of 1560 patients (59±14 years; 70% male) were enrolled. Mean LVEF was 45±18% and 1049 patients (67%) had hyperenhanced tissue (HE) on DE-CMR indicative of damage. During a median follow-up time of 2.4 years (IQR 1.2, 2.9 years), 176 patients (11.3%) died. Patients who died were more likely to be older (p4 segments) had reduced survival compared to patients with ≤ median HE (p=0.02).

CONCLUSIONS: Both LVEF and amount of myocardial damage as assessed by routine CMR are independent predictors of all-cause mortality. Even in patients with near normal LVEF, significant damage identifies a cohort with high-risk for early mortality.

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Intra-Aortic Balloon Counterpulsation and Infarct Size in Patients With Acute Anterior Myocardial Infarction Without Shock: The CRISP AMI Randomized Trial

OBJECTIVES: Intra-aortic balloon counterpulsation (IABC) is an adjunct to revascularization in patients with cardiogenic shock and reduces infarct size when placed prior to reperfusion in animal models.To determine if routine IABC placement prior to reperfusion in patients with anterior ST-segment elevation myocardial infarction (STEMI) without shock reduces myocardial infarct size.

METHODS: An open, multicenter, randomized controlled trial, the Counterpulsation to Reduce Infarct Size Pre-PCI Acute Myocardial Infarction (CRISP AMI) included 337 patients with acute anterior STEMI but without cardiogenic shock at 30 sites in 9 countries from June 2009 through February 2011.Intervention Initiation of IABC before primary percutaneous coronary intervention (PCI) and continuation for at least 12 hours (IABC plus PCI) vs primary PCI alone.Main Outcome Measures Infarct size expressed as a percentage of left ventricular (LV) mass and measured by cardiac magnetic resonance imaging performed 3 to 5 days after PCI. Secondary end points included all-cause death at 6 months and vascular complications and major bleeding at 30 days. Multiple imputations were performed for missing infarct size data.

RESULTS: The median time from first contact to first coronary device was 77 minutes (interquartile range, 53 to 114 minutes) for the IABC plus PCI group vs 68 minutes (interquartile range, 40 to 100 minutes) for the PCI alone group (P = .04). The mean infarct size was not significantly different between the patients in the IABC plus PCI group and in the PCI alone group (42.1% [95% CI, 38.7% to 45.6%] vs 37.5% [95% CI, 34.3% to 40.8%], respectively; difference of 4.6% [95% CI, -0.2% to 9.4%], P = .06; imputed difference of 4.5% [95% CI, -0.3% to 9.3%], P = .07) and in patients with proximal left anterior descending Thrombolysis in Myocardial Infarction flow scores of 0 or 1 (46.7% [95% CI, 42.8% to 50.6%] vs 42.3% [95% CI, 38.6% to 45.9%], respectively; difference of 4.4% [95% CI, -1.0% to 9.7%], P = .11; imputed difference of 4.8% [95% CI, -0.6% to 10.1%], P = .08). At 30 days, there were no significant differences between the IABC plus PCI group and the PCI alone group for major vascular complications (n = 7 [4.3%; 95% CI, 1.8% to 8.8%] vs n = 2 [1.1%; 95% CI, 0.1% to 4.0%], respectively; P = .09) and major bleeding or transfusions (n = 5 [3.1%; 95% CI, 1.0% to 7.1%] vs n = 3 [1.7%; 95% CI, 0.4% to 4.9%]; P = .49). By 6 months, 3 patients (1.9%; 95% CI, 0.6% to 5.7%) in the IABC plus PCI group and 9 patients (5.2%; 95% CI, 2.7% to 9.7%) in the PCI alone group had died (P = .12).

CONCLUSIONS: Among patients with acute anterior STEMI without shock, IABC plus primary PCI compared with PCI alone did not result in reduced infarct size.

PMID: 21878431

Safety of Serial MRI in Patients With Implantable Cardioverter Defibrillators

OBJECTIVES: While patients with cardiac implantable electronic devices could benefit from magnetic resonance (MR) imaging, the presence of such devices has been designated as an absolute contraindication to MR. Although scanning algorithms are proposed for cardiac implantable electronic devices, their safety remains uncertain. To address this issue, the safety of serial cardiac MR scans was evaluated in patients with implantable cardioverter defibrillators (ICDs).

METHODS: Three serial cardiac MR scans were prospectively performed at 1.5 T on 10 patients (9 men) of median age 56 years (range 51–68) with ICDs. ICD interrogation was performed before and after the MR scan and at a follow-up of median 370 days (range 274–723). Image quality was also assessed.

RESULTS: In all patients MR scanning occurred without complications. There were no differences between pre- and post-MR pacing capture threshold, pacing lead or high voltage lead impedance, or battery voltage values. During follow-up there were no occurrences of ICD dysfunction. Although most patients had image artifacts, the studies were generally diagnostic regarding left ventricular function and wall motion. Delayed enhancement imaging was of good quality for inferior wall and inferolateral infarcts, but ICD artifacts often affected the imaging of anterior wall infarcts.

CONCLUSIONS: Serial MR scans at 1.5 T in patients with ICDs, when carefully performed in a monitored setting, have no adverse effects on either patient or device. When required, single or multiple MR scans at 1.5 T may therefore be considered for clinical diagnostic purposes in these patients.

PMID: