Takotsubo Cardiomyopathy: Overrepresentation of Cases

I read the report “Demographic and Co-Morbid Predictors of Stress (Takotsubo) Cardiomyopathy.” The investigators stated that 24,701 cases of stress cardiomyopathy were identified from the 2008 and 2009 Nationwide Inpatient Sample databases using International Classification of Diseases, Ninth Revision, Clinical Modification code of 42983. This number of cases appears too large, considering the rarity of the condition. It probably included admissions for acute myocardial infarction, considering that the 2 conditions have very similar clinical presentations. Although the correct International Classification of Diseases, Ninth Revision, Clinical Modification code for stress cardiomyopathy was used, it was not clear in the “Methods” section whether the investigators limited the case selection to the first listed diagnosis only or searched for cases using all listed diagnoses. On the Nationwide Inpatient Sample Web site, it is stated that the first listed diagnosis might not be the principal diagnosis, suggesting that stress cardiomyopathy diagnosis could be listed at any position. This suggests that stress cardiomyopathy and acute myocardial infarction could be listed as differential diagnoses in any of the admissions. Because of this, the investigators should have excluded cases of stress cardiomyopathy that also had acute myocardial infarction listed as a differential diagnosis. Not doing so could alter the measures of association, particularly when the stress cardiomyopathy cases were compared to the myocardial infarction control arm.

Furthermore, the investigators also noted that 69% of cases of stress cardiomyopathy were confirmed by angiography or cardiac catheterization. This might not be totally correct. Nationwide Inpatient Sample databases show only whether patients underwent the procedure and do not include the findings. The fact that a patient underwent the procedure during an admission does not confirm the stress cardiomyopathy diagnosis. I think it would be more appropriate to state that 69% of the patients admitted for stress cardiomyopathy underwent angiography and exclude those who did not from further analysis.

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Dec 7, 2016 | Posted by in CARDIOLOGY | Comments Off on Takotsubo Cardiomyopathy: Overrepresentation of Cases

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