MDCT demonstrates high interobserver variability and has only modest diagnostic accuracy for the detection of left atrial thrombus in patients undergoing AFA procedure. Potential factors affecting the accuracy of MDCT include image quality and the difficulty of distinguishing clot from pectinate muscle. MDCT likely is not the optimal method to detect left atrial thrombus using current techniques and standards of interpretation.
Calcium score (CS) is a useful tool in evaluating the risk of cardiovascular events in asymptomatic patients. The absence of detectable calcification determines excellent cardiovascular prognosis, with event rates lower than that of negative stress studies, probably due to the latter's inability to detect nonobstructive coronary artery disease (CAD). There are few primary prevention medications that would be cost-effective in such a low-risk patient population. The interval for retesting patients with zero CS is still open for debate but it should not be in less than 4 to 5 years. CS should not be used to rule out obstructive CAD in symptomatic patients, as its correlation with coronary stenosis is poor and obstructive CAD is commonly found among symptomatic zero CS patients. Most studies have found very low specificity values for CS to detect obstructive CAD in symptomatic patients, meaning it has limited ability to detect the true negative cases (ie, zero CS without obstructive CAD).
Bypass surgery has been shown to prolong life in patients with significant left main stenosis compared with medical therapy and is the current standard of care. Recent registry data suggest that stenting may offer intermediate-term results similar to surgery, although with a greater need for repeat revascularization. Drug-eluting stents appear to improve the outcomes of stenting. Over 20% of patients with left main disease currently receive stents, and there is need for ongoing randomized controlled trials to validate this approach. It is essential that such patients receive balanced counseling as to revascularization options.
Since the beginnings of cardiac angiography, iodinated contrast has been the one and, until recently, only family of X-ray-attenuating agents with the safety and effectiveness to warrant clinical use. Over the last half century, considerable effort has been expended to improve these dyes by addressing side effects that, while tolerable in the vast majority of patients, could result in significant morbidity and even mortality in a few. The development of low osmolal and iso-osmolal contrast has gone far in achieving this goal by reducing the incidence and/or severity of most adverse events, including contrast-associated nephrotoxicity (CAN). The importance of any nephrotoxicity, however, has been magnified by recent studies linking the short-and long-term outcome of patients undergoing percutaneous coronary intervention to the occurrence of renal failure (both acute and chronic). Thus, it is not only the infrequent patient who requires hemodialysis or ultrafiltration for acute renal failure following angiography that we are concerned with, but also the individual who might transiently increase his serum creatinine by as little as 0.5 mg/dL.Despite the attention given to CAN, there appears to be little that can be done to prevent it. Periprocedural hydration and the use of low osmolal contrast are generally accepted as being effective prophylaxis while acetylcysteine and iso-osmolal nonioinic contrast are still considered unproven by many. However, as every angiographer knows, the use of all of these measures does not guarantee the prevention of nephropathy. The search for alternative contrast led to gadolinium-containing compounds used for magnetic resonance studies. Our radiology colleagues first demonstrated that these agents were safe and effective in patients at high risk for CAN when used in renal artery digital subtraction angiography and intervention. Direct coronary angiography using gadolinium, alone or combined with iodinated contrast, has been reported in relatively few patients. The diagnostic quality of such angiography has been in general suboptimal but there does not seem to be significant renal toxicity with the dosage of gadolinium used.In this issue, Voss et al. [1] describe three patients at risk for CAN in which coronary angiography was performed with gadobutrol. This agent, not yet approved in the United States, was formulated as a 1 mol/L solution and thus is twice as concentrated as other gadolinium contrasts. Because of this, one might expect more X-ray attenuation per given volume of this agent. The three patients received a total of 35-75 ml of gadobutrol or 0.52-1.21 ml/kg of body weight, although the maximum recommended dose is 0.5 mmol/kg of body weight. While the coronary angiograms were said to be diagnostic, the one ventriculogram performed with 25 cc of gadobutrol was underopacified and nondiagnostic. There was no evidence of nephrotoxicity.One should note that the patients received only four coronary injections and had already exceeded the recommended dose of the contrast. It is r...
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