TTE and TEE, or Just TEE? That is the Question
ABSTRACT & COMMENTARY
Source: McNamara RL, et al. Echocardiographic identification of cardiovascular sources of emboli to guide clinical management of stroke: A cost-effectiveness analysis. Ann Intern Med 1997;127:775-787.
Despite the fact that up to 45% of all strokes are embolic in origin,1 there is no consensus regarding the indications for cardiovascular imaging. Some neurologists routinely order transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in all patients with no obvious clinical cause of stroke. Others order TEE in accordance with the patient’s clinical history or only on the recommendation of a cardiology consultant.
To evaluate the benefits, risks, and costs of different diagnostic approaches, McNamara and colleagues performed a cost-effectiveness analysis of nine common cardiovascular diagnostic strategies, including TTE, TEE, sequential approaches, selective imaging, and no imaging. Echocardiographic detection rates of sources of emboli were ascertained by a systematic review of the literature. Values for event rates, anticoagulation effects, utilities, and costs were obtained from the literature and Medicare data.
In a hypothetical cohort of patients in NSR with a first stroke, the diagnostic strategies employing TEE identified the most patients (59%) with left atrial thrombi. Strategies employing only TTE identified up to 20% of these patients. When visualized left atrial thrombus was used as the only indication for anticoagulation, TEE in all patients cost $13,000 per quality-adjusted life year. Cost savings and decreased morbidity and mortality rates associated with reduction in preventable recurrent strokes substantially offset examination costs. TTE alone or in sequence with TEE was not cost-effective compared with TEE alone. Therefore, the authors recommend that physicians consider performing TEE in all patients with new onset stroke.
COMMENTARY
The authors have approached the issue of secondary prevention of stroke from a societal perspective. They calculated that TEE in all patients after an initial stroke would cost $13,000 per quality-adjusted life year. This should be compared with the cost of other common medical interventions, for example $50,000 per quality-adjusted life year for hemodialysis in end-stage renal disease2 and $12,000-$64,000 per quality-adjusted life year for the pharmacologic treatment of hypertension.3
The cost effectiveness of TEE derives from three factors: 1) TEE is very sensitive and relatively specific for identifying left atrial thrombus, whereas TTE is not; 2) the cost of TEE is relatively low; and most important, 3) cost savings from a small reduction in recurrent stroke compensate for the cost of using TEE as a universal screening test in patients of appropriate age and having historical risk factors.
This study is limited by its retrospective analysis of heterogeneous data. Therefore, any conclusions derived from the complex methods used in meta-analysis also must be considered from the perspectives of clinical experience and common sense.4 In this case, however, the authors’ analysis confirms a common clinical impressionnamely that TEE is useful in identifying patients who are at high risk for subsequent embolic stroke. This study supports the cost-effectiveness of a "valuable" test. jjc
References
1. The Cerebral Embolism Task Force. Arch Neurol 1989;46:727-743.
2. Garner TI, Dardis R. Med Care 1987;25:25-34.
3. Kupersmith J, et al. Prog Cardiovasc Dis 1995;37:243-71.
4. Lau T, et al. Ann Intern Med 1997;127:820-826.
In patients with an initial stroke, TEE was cost-effective in which of the following subgroups?
a. Patients with a history of cardiac problems
b. Patients without a history of cardiac problems
c. Patients in normal sinus rhythm
d. Patients who did not have a TTE
e. All of the above
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