Our study showed that 3-T CMR perfusion imaging is superior to 1.5-T for prediction of significant single- and multi-vessel coronary disease, and 3-T may become the preferred CMR field strength for myocardial perfusion assessment in clinical practice.
Background-Obesity is characterized by impaired cardiac energetics, which may play a role in the development of diastolic dysfunction and inappropriate shortness of breath. We assessed whether, in obesity, derangement of energetics and diastolic function is further altered during acute cardiac stress. Methods and Results-Normal-weight (body mass index, 22Ϯ2 kg/m 2 ; nϭ9 -17) and obese (body mass index, 39Ϯ7 kg/m 2 ; nϭ17-46) subjects underwent assessment of diastolic left ventricular function (cine magnetic resonance imaging volume-time curve analysis) and cardiac energetics (phosphocreatine/ATP ratio; 31 P-magnetic resonance spectroscopy) at rest and during dobutamine stress (heart rate increase, 65Ϯ22% and 69Ϯ14%, respectively; Pϭ0.61). At rest, obesity was associated with a 22% lower peak filling rate (PϽ0.001) and a 15% lower phosphocreatine/ATP ratio (1.73Ϯ0.40 versus 2.03Ϯ0.28; Pϭ0.048). Peak filling rate correlated with fat mass, left ventricular mass, leptin, waist-to-hip ratio, and phosphocreatine/ATP ratio. On multivariable analysis, phosphocreatine/ATP was the only independent predictor of peak filling rate (ϭ0.50; Pϭ0.03). During stress, a further reduction in phosphocreatine/ATP occurred in obese (from 1.73Ϯ0.40 to 1.53Ϯ0.50; Pϭ0.03) but not in normal-weight (from 1.98Ϯ0.24 to 2.04Ϯ0.34; Pϭ0.50) subject. For similar levels of inotropic stress, there were smaller increases in peak filling rate in obesity (38% versus 70%; Pϭ0.01). Conclusions-In
Aims: Myocardial revascularisation improves outcomes in patients with coronary artery disease. However, these procedures may themselves cause irreversible myocardial injury. The prognostic value of procedural myocardial injury is uncertain. Methods and results: We quantified procedural myocardial necrosis using delayed enhancement cardiovascular magnetic resonance imaging (DE-CMR) in 152 consecutive patients before and shortly after percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG). The primary endpoint was defined as death, non-fatal myocardial infarction, sustained ventricular arrhythmia, unstable angina or heart failure requiring hospitalisation. During a median follow-up of 2.9 years, 27 patients (18%) reached the primary endpoint. 49 patients (32%) had evidence of new procedure-related myocardial hyperenhancement with a median mass of 5.0 g (interquartile range 2.7-9.8). After adjustment for age and sex, these patients had a 3.1-fold (95% confidence interval 1.4 to 6.8; p = 0.004) higher risk of adverse outcome than patients without new hyperenhancement. Cardiac troponin levels and quantitative measures of left ventricular function after procedure did not show any significant independent association with the primary endpoint and they did not alter the independent association of new hyperenhancement. Conclusions: Myocardial injury during PCI or CABG, identified by DE-CMR, adversely affects clinical outcome. This suggests the benefits from revascularisation could partially be offset by new myocardial injury caused by the intervention itself.A rise in cardiac biomarkers occurs in nearly all patients undergoing coronary artery bypass graft (CABG) surgery 1 and in up to 40% of patients undergoing percutaneous coronary intervention (PCI).2 The most recent joint European Society of Cardiology (ESC)/American College of Cardiology (ACC)/American Heart Association (AHA)/World Heart Federation (WHF) task force guidelines recognise elevation of cardiac biomarkers of more than three times the 99th percentile upper reference limit (URL) following PCI and more than five times the 99th percentile URL after CABG in the definition of procedure-related myocardial infarction. 3 However, controversy remains over the independent prognostic value of rises in biomarkers after revascularisation. Although biomarkers such as troponin have a high accuracy in detection of myocardial tissue loss and have been shown to be of prognostic value in several acute and non-acute settings, the demonstration of their prognostic value after coronary revascularisation has been hampered for several reasons: troponin elevations after revascularisation are often very small and the cut-offs for abnormal values variable across studies; many patients undergoing elective revascularisation have some degree of troponin elevation before the procedure 6 7; the inherent delay in rise of biomarkers may affect the correct ascertainment of sequence of events, 8 in particular when revascularisation itself can lead to biomarke...
BackgroundThe new gold standard for myocardial viability assessment is late gadolinium enhancement-cardiovascular magnetic resonance (LGE-CMR); this technique has demonstrated that the transmural extent of scar predicts segmental functional recovery. We now asked how the number of viable and number of viable+normal, segments predicted recovery of global left ventricular (LV) function in patients undergoing CABG. Finally, we examined which segmental transmural threshold of scarring best predicted global LV recovery.Methods and ResultsFifty patients with reduced LV ejection fraction (EF) referred for CABG were recruited, and 33 included in this analysis. Patients underwent CMR to assess LV function and viability pre-operatively at 6 days and 6 months. Mean LVEF 38% ± 11, which improved to 43% ± 12 after surgery. 21/33 patients improved EF by ≥3% (EF before 38% ± 13, after 47% ± 13), 12/33 did not (EF before 39% ± 6, after 37% ± 8). The only independent predictor for global functional recovery after revascularisation was the number of viable+normal segments: Based on a segmental transmural viability cutoff of <50%, ROC analysis demonstrated ≥10 viable+normal segments predicted ≥3% improvement in LVEF with a sensitivity of 95% and specificity of 75% (AUC = 0.9, p < 0.001). Transmural viability cutoffs of <25 and <75% and a cutoff of ≥4 viable segments were less useful predictors of global LV recovery.ConclusionsBased on a 50% transmural viability cutoff, patients with ≥10 viable+normal segments improve global LV function post revascularisation, while patients with fewer such segments do not. LGE-CMR is a simple and powerful tool for identifying which patients with impaired LV function will benefit from CABG.Trial registrationResearch Ethics Committee Unique Identifier: NRES:05/Q1603/42. The study is listed on the Current Controlled Trials Registry: ISRCTN41388968.URL: http://www.controlled-trials.com
Background-Beating heart coronary artery bypass grafting (CABG) improves early postoperative cardiac function in patients with normal ventricular function, but its effect in patients with impaired function is uncertain. We compared a novel hybrid technique of on-pump beating heart CABG (ONBEAT) with conventional on-pump CABG (ONSTOP) in patients with impaired ventricular function. Methods and Results-In a single-center randomized trial, 50 patients with impaired ventricular function were randomly assigned to ONBEAT or ONSTOP. Patients underwent cardiac magnetic resonance imaging for function and delayed hyperenhancement early and later after surgery. Serial assessment of biochemical markers was also undertaken. Preoperative characteristics were well matched; cardiac index was 2.85Ϯ0.53 (ONBEAT) and 2.62Ϯ0.59 L · min Ϫ1 · m Ϫ2 (ONSTOP). Early after surgery, there was a trend toward a greater reduction in end-systolic volume index in ONSTOP patients versus ONBEAT (Ϫ9Ϯ8 versus Ϫ4Ϯ11 mL · m Ϫ2 ; Pϭ0.06). The changes were sustained and significant at 6 months (Ϫ14Ϯ18 versus Ϫ2Ϯ19 mL · m Ϫ2 ; Pϭ0.04). Furthermore, the incidence of new hyperenhancement at 6 days was higher in ONBEAT patients (Pϭ0.05), with 6 of 17 (35%) sustaining 8.2Ϯ5.2 g of new hyperenhancement each versus 2 of 23 (9%) in the ONSTOP group, each with 9.8Ϯ9.0 g (Pϭ0.86). Finally, median area under the curve for troponin was higher in ONBEAT at 461 (interquartile range, 226 to 1141) g/L versus 160 (interquartile range, 98 to 357) g/L for ONSTOP (Pϭ0.002). Conclusions-The incidence of new irreversible myocardial injury was significantly higher in ONBEAT than in ONSTOP patients. Furthermore, at 6 months, only ONSTOP patients demonstrated an improvement in ventricular geometry. The most likely mechanism is inadequate coronary perfusion to distal myocardial territories in patients with severe proximal coronary disease. (Circulation. 2008;118:2130-2138.)
Biomarkers alone (TnI), at an appropriate threshold appear robust for the detection of type V MI, independently of supplementary evidence, as suggested by the ESC/ACCF/AHA/WHF criteria. Clinical trial registration information The study is listed on the Current Controlled Trials Registry: ISRCTN41388968. URL: http://www.controlled-trials.com.
Background-The pathophysiology of chest pain in patients with cardiac syndrome X remains controversial. Advances in perfusion imaging with cardiovascular magnetic resonance (CMR) now enable absolute quantification of regional myocardial blood flow (MBF). Furthermore, blood oxygen level-dependent (BOLD) or oxygenation-sensitive CMR provides the unprecedented capability to assess regional myocardial oxygenation. We hypothesized that the combined assessment of regional perfusion and oxygenation with CMR could clarify whether patients with syndrome X show evidence of myocardial ischemia (reduced perfusion and oxygenation) during vasodilator stress compared with normal volunteers. Methods and Results-Eighteen patients with syndrome X (chest pain, abnormal exercise treadmill test, normal coronary angiogram without other causes of microvascular dysfunction) and 14 controls underwent CMR scanning at 3 T. Myocardial function, scar, perfusion (2-3 short-axis slices), and oxygenation were assessed. Absolute MBF was measured during adenosine stress (140 g/kg per minute) and at rest by model-independent deconvolution. For oxygenation, using a T2-prepared BOLD sequence, signal intensity was measured at adenosine stress and rest in the slice matched to the midventricular slice of the perfusion scan. There were no significant differences in MBF at stress (
We sought to assess the tolerance and safety of adenosine-stress cardiovascular magnetic resonance (CMR) perfusion imaging in patients with coronary artery disease (CAD). We retrospectively examined all adenosine CMR perfusion scans performed in our centre in patients with known or suspected (CAD) and normal volunteers at either 1.5 or 3 T. All subjects were initially screened for contraindications to adenosine. The dose of adenosine infused was 140 microg/kg/min. Significant CAD was defined angiographically as the presence of at least one stenosis of >50% diameter. Data were collected from 351 consecutive subjects (mean age 62 +/- 11 years, range 25-85 years-245 men). Of the 351 subjects, 305 had a coronary angiogram, the remaining 46 subjects were normal volunteers studied for research protocols. In total, 233 subjects (76%) were found to have significant CAD of whom 128 had multi-vessel disease. There were no deaths, myocardial infarctions, or episodes of bronchospasm during the CMR study. Transient 2nd (Mobitz II) or 3rd-degree atrioventricular (AV) block occurred in 27 patients (8%). There were no sustained episodes of advanced AV block. Transient chest pain was the most common side effect (199 subjects-57%). The use of intravenous adenosine in CMR perfusion imaging is safe and well-tolerated, even in patients with severe CAD. Where a careful screening policy for contraindications to adenosine is followed, serious adverse events in the CMR scanner are relatively rare and symptoms resolve following termination of the infusion, without the need for aminophylline.
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