Heavy snowfall, cold temperatures, and low atmospheric pressure during the winter months have been associated with increased adverse cardiovascular events. However, only a few cases of the “snow shoveler’s infarction” have been reported. The investigators describe their experience with 6 patients presenting with ST elevation myocardial infarctions, all within a 24-hour period during an unprecedented snowfall (4 of whom were shoveling snow), and provide a detailed review of previously reported cases of snow shoveler’s infarction. Consistent with other reports, most patients reported here had the traditional cardiac risk factors of hypertension, hyperlipidemia, diabetes mellitus, tobacco use, and sedentary lifestyle. Unique to this case series, however, was that the 4 patients who had histories of coronary artery disease and previous coronary artery stenting all presented with subacute stent thromboses documented on coronary angiography performed emergently. Moreover, these patients constituted 25% of all subacute stent thromboses diagnosed in the cardiac catheterization laboratory in the preceding 12 months. In conclusion, these findings suggest that in typically sedentary individuals with cardiac risk factors or histories of coronary artery disease, snow shoveling may trigger ST elevation myocardial infarction and therefore should be avoided. This may be most critical in patients with histories of coronary stent placement, considering that these findings suggest that snow shoveling may precipitate subacute stent thrombosis.
Adverse cardiac events, including acute myocardial infarction and sudden cardiac death, may be triggered during and after major snowstorms by colder temperatures and the physical exertion expended with snow shoveling. We present a case series of 6 patients who presented with acute ST elevation myocardial infarctions (STEMIs), all within a 24-hour period during an unprecedented snowfall, 4 of whom experienced symptoms while shoveling snow. Patients with histories of coronary artery disease and previous coronary stent placement all presented with subacute stent thromboses, a unique presentation that has not been previously described in other cases of “snow shoveler’s infarction.”
Case Descriptions
In a 24-hour period from Saturday, December 19, 2009, to Sunday, December 20, 2009, 6 patients were taken emergently to the cardiac catheterization laboratory at the University of Virginia (Charlottesville, Virginia) with the diagnosis of STEMI; 4 underwent primary percutaneous coronary intervention, and 2 underwent rescue percutaneous coronary intervention after failed thrombolysis. Medical histories, medications on admission, laboratory values, 12-lead electrocardiographic results, treatment delay, angiographic findings, procedural details, and in-hospital outcomes for all patients were recorded.
We searched published research for reported cases of “snow shoveler’s infarction.” We reviewed the Medline database for reports from 1970 to 2010. The following key words were used in the search: “ST elevation myocardial infarction,” “acute coronary syndrome,” “infarction,” “snow,” “snow shoveling,” “snow blowing,” and “snow removal.” We reviewed only reports written in English. We also gathered meteorologic data from the McCormick Observatory, located on the campus of the University of Virginia, for the time period from December 18, 2009, to December 20, 2009 (data from previous months were reviewed for comparison). Last, we searched our cardiac catheterization laboratory database to determine the daily number of patients with STEMIs referred for primary percutaneous coronary intervention and the daily number of STEMIs caused by subacute stent thromboses from December 2008 to December 2009.
The baseline characteristics of the patients are listed in Table 1 . Of the 6 patients, 4 had histories of stent placement (2 with drug-eluting stents and 2 with bare-metal stents; Table 1 ); all 4 patients presented with subacute stent thromboses, and all but 1 were receiving long-term dual-antiplatelet therapy. Symptom onset to arrival in the emergency department ranged from 40 to 264 minutes. The infarct-related artery was the left anterior descending coronary artery in 3 patients and the right coronary artery in 3 patients; all patients underwent intervention on the infarct-related artery, and 1 patient required an intra-aortic balloon pump. New congestive heart failure was diagnosed in 3 patients, and 1 patient died from cardiogenic shock.
| Patient | Age (years) | Gender | Race | Engaged in Snow Removal | HTN | ↑ Lipids | DM | CS | Previous MI | Previous Stent ⁎ | Previous AP | β Blocker | ACE Inhibitor/ARB | Statins | Aspirin | Clopidogrel | ECG Location of ST Elevation | Initial Troponin (μg/L) | Peak Troponin (μg/L) | Creatinine (mg/dl) | WBC Count (×10 3 /mm 3 ) | HbA 1c (%) | TC (mg/dl) | LDL (mg/dl) | HDL (mg/dl) | Triglycerides (mg/dl) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 44 | M | W | + | 0 | + | + | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | II, III, aVF | 0.25 | 292 | 0.9 | 21.9 | 6.1 | 139 | 106 | 26 | 44 |
| 2 | 51 | M | W | + | + | + | 0 | + | + | + | 0 | 0 | + | + | + | + | II, III, aVF | 0.02 | 46.85 | 1.3 | 10.12 | 5.7 | 164 | 110 | 39 | 89 |
| 3 | 58 | F | W | + | + | + | 0 | + | 0 | + | 0 | + | + | + | + | + | V 1 –V 2 , I, aVL | 89.68 | 194.94 | 0.6 | 12.90 | 5.8 | 148 | 85 | 45 | 107 |
| 4 | 59 | M | W | + | + | + | 0 | + | + | + | 0 | 0 | + | + | + | 0 | II, III, aVF, V 5 –V 6 | 0.10 | 37.53 | 1.4 | 12.66 | 6.0 | 142 | 93 | 33 | 97 |
| 5 | 72 | F | W | 0 | + | + | + | 0 | + | + | 0 | + | + | + | + | + | V 1 –V 3 , new RBBB | >440.0 | >440.0 | 1.3 | 13.97 | 8.3 | 172 | 114 | 43 | 87 |
| 6 | 83 | F | W | 0 | + | 0 | + | 0 | 0 | 0 | 0 | + | 0 | 0 | 0 | 0 | V 1 –V 3 | 0.12 | 293 | 0.8 | 22.5 | 5.9 | 134 | 86 | 35 | 80 |
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