{ "docId": "019dd923-622c-750b-8b98-08d95731b035", "docSlug": "4dea9707af58", "documentTitle": "AtriCure, Inc. (ATRC)", "authorId": "53_Kerrisdale_Capital", "authorName": "Kerrisdale Capital", "documentKindSlug": "research-note", "documentKindLabel": "Research note", "sourceTypeSlug": "short_seller", "sourceTypeLabel": "Short seller", "presentationDate": "2020-09-01 00:00:00", "orientation": "portrait", "aspectRatio": 0.77272725, "pageNumber": 22, "pageCount": 34, "prevPage": 21, "nextPage": 23, "slideType": "expose_contradiction", "function": "expose_contradiction", "density": "overcrowded", "nDataPoints": 0, "notes": "The slide uses a bulleted list to systematically dismantle the credibility of a research study.", "elementsJson": [ "paragraph", "bullet_list", "footnote" ], "metadataConfidence": 1, "imagePath": null, "slideHref": "/slides/019dd923-622c-750b-8b98-08d95731b035/22", "deckHref": "/decks/019dd923-622c-750b-8b98-08d95731b035", "deckJsonHref": "/decks/019dd923-622c-750b-8b98-08d95731b035.json", "deckAnchorHref": "/decks/019dd923-622c-750b-8b98-08d95731b035#slide-22", "components": [ { "bbox": { "h": 0.025, "w": 0.425, "x": 0.118, "y": 0.223 }, "kind": "callout", "text": "But an even cursory review of the study reveals its shoddiness:", "attrs": null, "subkind": "primary", "toolName": null, "toolSlug": null, "confidence": null, "componentId": "2e8e8b5b-97aa-4dc8-9ee7-d4a964038fe3", "frameworkName": null, "frameworkSlug": null }, { "bbox": { "h": 0.215, "w": 0.775, "x": 0.118, "y": 0.448 }, "kind": "list", "text": "Medicare data doesn’t actually report whether a patient undergoing open-heart surgery has AF. So the AtriCure investigators matched patient data with hospital admissions in the prior 3 years, and if a patient had 1 hospital admission with a diagnosis code corresponding to AF in that time, the patient would be considered to have preoperative AF. The authors admit that a “hospital admission with a diagnosis of AF” is actually “not specific for the presence of AF” and “could be used for admission to rule out AF.” One thing the study authors don’t admit is that the AF diagnosis code could also have been related to an actual ablation – catheter or surgical – which, of course, would mean the patient was not a subsequent candidate for a concomitant ablation. Such glaring flaws in the basic classification of the data apparently did not give much pause to the study authors.", "attrs": null, "subkind": "bullet", "toolName": null, "toolSlug": null, "confidence": null, "componentId": "519574ea-e44b-4512-97d8-2d6e09505bd7", "frameworkName": null, "frameworkSlug": null }, { "bbox": { "h": 0.085, "w": 0.775, "x": 0.118, "y": 0.778 }, "kind": "list", "text": "10% of the Medicare sample used by the AtriCure study was comprised of patients with endocarditis or undergoing a repeat or follow-up procedure. The former category is contra-indicated for an ablation, and the inclusion of the latter category is double counting in the denominator, as if an ablation would be performed, it could only be performed in one of the procedures.", "attrs": null, "subkind": "bullet", "toolName": null, "toolSlug": null, "confidence": null, "componentId": "575b4287-0d71-47ae-9182-028a0e0570f9", "frameworkName": null, "frameworkSlug": null }, { "bbox": { "h": 0.095, "w": 0.775, "x": 0.118, "y": 0.258 }, "kind": "list", "text": "Though the investigators had access to the STS database, which covers over 95% of surgical procedures, they instead chose to use the much sparser Medicare data series for only one year, 2014, which is strange considering that there is more recent Medicare data to evaluate. The Medicare database included only a quarter of the total open-heart procedures captured by the STS database.", "attrs": null, "subkind": "bullet", "toolName": null, "toolSlug": null, "confidence": null, "componentId": "7ec94665-e907-45a9-985c-b784dcfc9a77", "frameworkName": null, "frameworkSlug": null }, { "bbox": { "h": 0.095, "w": 0.775, "x": 0.118, "y": 0.353 }, "kind": "list", "text": "The major bias of Medicare data is that it only includes Medicare patients, a population that is massively different from the average patient who undergoes open-heart surgery. The median patient with AF in the AtriCure study was a few years over 75, while the median patient with AF in the STS database was 71 years old. The gap of over 5 years explains at least some of the difference in preoperative AF rates.", "attrs": null, "subkind": "bullet", "toolName": null, "toolSlug": null, "confidence": null, "componentId": "be5057b0-dfd8-45db-a247-382e08fa9ec6", "frameworkName": null, "frameworkSlug": null }, { "bbox": { "h": 0.115, "w": 0.775, "x": 0.118, "y": 0.663 }, "kind": "list", "text": "20% of the procedures in the Medicare sample were classified as emergency surgery, while that category represents about 3.5% of the overall patients undergoing open heart surgery in the STS database. Unsurprisingly, patients undergoing emergency surgery are extremely unlikely to undergo any concomitant procedure besides the one for which they were rushed to the hospital. The penetration rate of ablation in a sample with an inordinate number of emergency surgeries will necessarily be much lower than an unbiased sample of patients.", "attrs": null, "subkind": "bullet", "toolName": null, "toolSlug": null, "confidence": null, "componentId": "dd4976c0-3f48-4d28-a53e-a1ca8c688f0e", "frameworkName": null, "frameworkSlug": null }, { "bbox": { "h": 0.135, "w": 0.775, "x": 0.118, "y": 0.093 }, "kind": "paragraph", "text": "reported a financial relationship with AtriCure (including two employees of the company), and which was explicitly described as sponsored by AtriCure, a group of investigators found that the prevalence of AF in patients undergoing cardiac surgery was “substantially higher” than previously published rates of preoperative AF (i.e., the rates exhibited in the STS database), and that concomitant ablation was performed in fewer than a quarter of relevant patients. Coincidentally, the numbers match the story AtriCure has been telling for the last ten years.", "attrs": null, "subkind": "paragraph", "toolName": null, "toolSlug": null, "confidence": null, "componentId": "120ed68a-7072-48ba-a69d-9b6d44bc069b", "frameworkName": null, "frameworkSlug": null }, { "bbox": null, "kind": "quote", "text": "The authors admit that a \"hospital admission with a diagnosis of AF\" is actually \"not specific for the presence of AF\" and \"could be used for admission to rule out AF.\"", "attrs": null, "subkind": null, "toolName": "Authority citation", "toolSlug": "authority-citation", "confidence": null, "componentId": "019dd953-0396-73da-b905-cae724811fa2", "frameworkName": null, "frameworkSlug": null }, { "bbox": { "h": 0.035, "w": 0.775, "x": 0.118, "y": 0.878 }, "kind": "source-note", "text": "19 McCarthy, PM, et al, Prevalence of atrial fibrillation before cardiac surgery and factors associated with concomitant ablation", "attrs": null, "subkind": null, "toolName": null, "toolSlug": null, "confidence": null, "componentId": "244617c8-bf50-4c8a-9e1a-fb78c4a00719", "frameworkName": null, "frameworkSlug": null } ], "metrics": [], "tools": [], "frameworks": [], "arcBeats": [], "loops": [], "imagePathAlt": null, "thumbSrc": null, "thumbSrcAlt": null, "locked": true }