Assessment of global myocardial perfusion reserve using cardiovascular magnetic resonance of coronary sinus flow at 3 Tesla.

BACKGROUND: Despite increasing clinical use, there is limited data regarding regadenoson in stress perfusion cardiovascular magnetic resonance (CMR). In particular, given its long half-life the optimal stress protocol remains unclear. Although Myocardial Perfusion Reserve (MPR) may provide additive prognostic information, current techniques for its measurement are cumbersome and challenging for routine clinical practice.The aims of this study were: 1) To determine the feasibility of MPR quantification during regadenoson stress CMR by measurement of Coronary Sinus (CS) flow; and 2) to investigate the role of aminophylline reversal during regadenoson stress-CMR. METHODS: 117 consecutive patients with possible myocardial ischemia were prospectively enrolled. Perfusion imaging was performed at 1 minute and 15 minutes after administration of 0.4 mg regadenoson. A subgroup of 41 patients was given aminophylline (100 mg) after stress images were acquired. CS flow was measured using phase-contrast imaging at baseline (pre CS flow), and immediately after the stress (peak CS flow) and rest (post CS flow) perfusion images. RESULTS: CS flow measurements were obtained in 92% of patients with no adverse events. MPR was significantly underestimated when calculated as peak CS flow/post CS flow as compared to peak CS flow/pre CS flow (2.43±0.20 vs. 3.28±0.32, p=0.03). This difference was abolished when aminophylline was administered (3.35±0.44 vs. 3.30±0.52, p=0.95). Impaired MPR (peak CS flow/pre CS flow<2) was associated with advanced age, diabetes, current smoking and higher Framingham risk score. CONCLUSIONS: Regadenoson stress CMR with MPR measurement from CS flow can be successfully performed in most patients. This measurement of MPR appears practical to perform in the clinical setting. Residual hyperemia is still present even 15 minutes after regadenoson administration, at the time of resting-perfusion acquisition, and is completely reversed by aminophylline. Our findings suggest routine aminophylline administration may be required when performing stress CMR with regadenoson.

Impact of cardiovascular magnetic resonance on management and clinical decision-making in heart failure patients.

BACKGROUND: Cardiovascular magnetic resonance (CMR) can provide important diagnostic and prognostic information in patients with heart failure. However, in the current health care environment, use of a new imaging modality like CMR requires evidence for direct additive impact on clinical management. We sought to evaluate the impact of CMR on clinical management and diagnosis in patients with heart failure. METHODS: We prospectively studied 150 consecutive patients with heart failure and an ejection fraction ≤ 50% referred for CMR. Definitions for "significant clinical impact" of CMR were pre-defined and collected directly from medical records and/or from patients. Categories of significant clinical impact included: new diagnosis, medication change, hospital admission/discharge, as well as performance or avoidance of invasive procedures (angiography, revascularization, device therapy or biopsy). RESULTS: Overall, CMR had a significant clinical impact in 65% of patients. This included an entirely new diagnosis in 30% of cases and a change in management in 52%. CMR results directly led to angiography in 9% and to the performance of percutaneous coronary intervention in 7%. In a multivariable model that included clinical and imaging parameters, presence of late gadolinium enhancement (LGE) was the only independent predictor of "significant clinical impact" (OR 6.72, 95% CI 2.56-17.60, p=0.0001). CONCLUSIONS: CMR made a significant additive clinical impact on management, decision-making and diagnosis in 65% of heart failure patients. This additive impact was seen despite universal use of prior echocardiography in this patient group. The presence of LGE was the best independent predictor of significant clinical impact following CMR.

Are changes in carotid intima-media thickness related to risk of nonfatal myocardial infarction? A critical review and meta-regression analysis.

BACKGROUND: Carotid intima-media thickness (CIMT) is increasingly being used as a surrogate end point in randomized control trials (RCTs) of novel cardiovascular therapies. However, it remains unclear whether changes in CIMT that result from these therapies correlate with nonfatal myocardial infarction (MI). METHODS: We performed a literature search of RCTs from 1990-2009 that used CIMT. Eligible RCTs (1) included quantitative and sequential assessments in CIMT at least 1 year apart and (2) reported nonfatal MI. Across RCTs, random-effects metaregression was employed to correlate differences in mean change in CIMT between treatment and control groups over time with the log odds ratios of developing nonfatal MI during follow-up. RESULTS: Overall, we identified 28 RCTs with 15,598 patients. Differences in mean change in CIMT over time between treatment and control groups correlated with developing nonfatal MI during follow-up: for each 0.01 mm per year smaller rate of change in CIMT, the odds ratio for MI was 0.82 (95% CI, 0.69 to 0.96; P = .018). Results were similar in subgroups of RCTs with >1 year follow-up (P = .018) and those with at least 50 subjects in the treatment group (P = .019). However, there was no significant relationship between mean change in CIMT and nonfatal MI in RCTs evaluating statin therapy or those with high CIMTs at baseline (P > .20 in both instances). CONCLUSIONS: Less progression in CIMT over time is associated with a lower likelihood of nonfatal MI in selected RCTs; however, these findings were inconsistent at times, suggesting caution in using CIMT as a surrogate end point.

Complications of transradial catheterization.

Cardiac catheterization via the transradial approach has increased in the United States over the past few years; however, wide-scale adoption still lags in comparison to many international health care systems. Transradial catheterization has a unique set of complications and risks that each operator must appreciate. Radial artery spasm and radial artery occlusion are the most common complications, while bleeding complications such as hematomas and perforations are much less frequent. Each of these issues can be managed successfully with minor changes to one's practice. In this review of the current state of the art, the reader will develop an appreciation for the prevalence of each of the common complications as well as the less common, but potentially highly morbid, events. Throughout this evidence-based review, practical prevention strategies and specific treatment pathways are described for each issue that is covered.