Complications after penetrating cardiac injury

Trauma specialists from Arizona and California describe patients with penetrating cardiac wounds, a quarter of whom survive to discharge. Survival post discharge is good, with a range of complications at follow up but no operative intervention was required for the complications.


HYPOTHESIS:
A significant rate of postdischarge complications is associated with penetrating cardiac injuries.

DESIGN: Retrospective trauma registry review.

SETTING: Level I trauma center.

PATIENTS: All patients sustaining penetrating cardiac injuries between January 2000 and June 2010. Patient demographics, clinical data, operative findings, outpatient follow-up, echocardiogram results, and outcomes were extracted.

MAIN OUTCOME MEASURES: Cardiac-related complications and mortality.

RESULTS: During the 10.5-year study period, 406 of 40,706 trauma admissions (1.0%) sustained penetrating cardiac injury. One hundred nine (26.9%) survived to hospital discharge. The survivors were predominantly male (94.4%), with a mean (SD) age of 30.8 (11.7) years, and 74.3% sustained a stab wound. Signs of life were present on admission in 92.6%. Cardiac chambers involved were the right ventricle (45.9%), left ventricle (40.3%), right atrium (10.1%), left atrium (0.9%), and combined (2.8%). In-hospital follow-up was available for a mean (SD) of 11.0 (9.8) days (median, 8 days; range, 3-65 days) and outpatient follow-up was available in 46 patients (42.2%) for a mean (SD) of 1.9 (4.1) months (median, 0.9 months; range, 0.2-12 months). Abnormal echocardiograms demonstrated pericardial effusions (9), abnormal wall motion (8), decreased ejection fraction (<45%) (8), intramural thrombus (4), valve injury (4), cardiac enlargement (2), conduction abnormality (2), pseudoaneurysm (1), aneurysm (1), and septal defect (1). No operative intervention was required for the complications. The 1-year and 9-year survival rates were 97% and 88%, respectively.
CONCLUSIONS: Penetrating cardiac injuries remain highly lethal. A significant rate of cardiac complications can be expected and follow-up echocardiographic evaluation is warranted prior to discharge. The majority of these, however, can be managed without the need for surgical intervention.

Postdischarge Complications After Penetrating Cardiac Injury: a survivable injury with a high postdischarge complication rate
Arch Surg. 2011 Sep;146(9):1061-6

Essential Retrieval Medicine Toolkit

Australian retrieval medicine guru and Flying Doctor Dr Minh Le Cong sent me a copy of the ‘Prehospital Anaesthesia and Airway management Syllabus 2012’ that he’d authored, a thorough and evidence-based approach to airway management for practioners involved in pre-hospital care and critical care transport.
In the surgical airway section, Minh describes the use of ultrasound as an adjunct to the identification of the cricothyroid membrane. It includes this image of Minh ultrasounding his own neck in his office.

I couldn’t help but be distracted by an object on his desk, which on closer inspection, appears to be a rubber chicken.

I emailed Minh to find out about that chicken. He replied:

..even I did not pick that my rubber chicken was visible in the shot!

A great tip from an ex SAS soldier…always carry a rubber chicken into high stress, high risk situations. You would be surprised how well it works in defusing high tension, arguments and standoffs as well as personally allowing you to take a moment and ground yourself when the shit is flying.

The chicken comes with me, along with my king vision, portable USS and Leatherman Multitool and head torch.I used all of those items recently on the same patient!

Minh Le Cong
Medical Education Officer
RFDS Queensland Section

What are the essential items you have with you on every shift? Is your list anything like Minh’s Retrieval Toolkit?

Predicting massive transfusion

Do you have access to thromboelastometry in your Emergency Department? Further research by some of the first discoverers of acute traumatic coagulopathy involved using this tool to identify acute traumatic coagulopathy at 5 mins and predict the need for massive transfusion. Measures of coagulopathy more familiar to ED staff such as the INR took longer or (when point-of-care testing was employed) were less accurate.


OBJECTIVE: To identify an appropriate diagnostic tool for the early diagnosis of acute traumatic coagulopathy and validate this modality through prediction of transfusion requirements in trauma hemorrhage.

DESIGN: Prospective observational cohort study.

SETTING: Level 1 trauma center.

PATIENTS: Adult trauma patients who met the local criteria for full trauma team activation. Exclusion criteria included emergency department arrival >2 hrs after injury, >2000 mL of intravenous fluid before emergency department arrival, or transfer from another hospital.

INTERVENTIONS: None.

MEASUREMENTS: Blood was collected on arrival in the emergency department and analyzed with laboratory prothrombin time, point-of-care prothrombin time, and rotational thromboelastometry. Prothrombin time ratio was calculated and acute traumatic coagulopathy defined as laboratory prothrombin time ratio >1.2. Transfusion requirements were recorded for the first 12 hrs following admission.

MAIN RESULTS: Three hundred patients were included in the study. Laboratory prothrombin time results were available at a median of 78 (62-103) mins. Point-of-care prothrombin time ratio had reduced agreement with laboratory prothrombin time ratio in patients with acute traumatic coagulopathy, with 29% false-negative results. In acute traumatic coagulopathy, the rotational thromboelastometry clot amplitude at 5 mins was diminished by 42%, and this persisted throughout clot maturation. Rotational thromboelastometry clotting time was not significantly prolonged. Clot amplitude at a 5-min threshold of ≤35 mm had a detection rate of 77% for acute traumatic coagulopathy with a false-positive rate of 13%. Patients with clot amplitude at 5 mins ≤35 mm were more likely to receive red cell (46% vs. 17%, p < .001) and plasma (37% vs. 11%, p < .001) transfusions. The clot amplitude at 5 mins could identify patients who would require massive transfusion (detection rate of 71%, vs. 43% for prothrombin time ratio >1.2, p < .001).
CONCLUSIONS: In trauma hemorrhage, prothrombin time ratio is not rapidly available from the laboratory and point-of-care devices can be inaccurate. Acute traumatic coagulopathy is functionally characterized by a reduction in clot strength. With a threshold of clot amplitude at 5 mins of ≤35 mm, rotational thromboelastometry can identify acute traumatic coagulopathy at 5 mins and predict the need for massive transfusion.

Functional definition and characterization of acute traumatic coagulopathy.
Crit Care Med. 2011 Dec;39(12):2652-2658

Modified ED thoracotomy to avoid exsanguination

Emergency physicians from Minnesota (and graduates of the amazing Hennepin Emergency Medicine Residency) describe a patient who developed cardiac tamponade after an ablation procedure for dysrhythmia. Attempts at pericardiocentesis by both emergency and cardiology staff were hindered by clotted blood, and so a left lateral thoracotomy was performed in the ED due to loss of pulse and lack of immediate availability of an operating room. A limited pericardial incision was made to allow drainage of sufficient blood to relieve tamponade while avoiding catastrophic blood loss from the underlying lesion, which turned out to be a 1.5-cm hole in the right ventricular outflow tract. The patient made a full recovery.

Cardiac dysrhythmias are a common problem in the United States. Radiofrequency ablation is being used more frequently as a treatment for these diagnoses. Although rare, serious complications such as cardiac tamponade have been reported as a result of ablation procedures. Traditionally, emergency department (ED) thoracotomy has been reserved for cases of traumatic arrest only. We report a case of a successful modified ED thoracotomy in a patient with postablation cardiac tamponade and subsequent obstructive shock who failed intravenous fluid resuscitation, pressor administration, and multiple attempts at pericardiocentesis. In this case, a modified approach was used to incise the pericardium. Although this was associated with large blood loss, we believed that using the traditional method of completely removing the pericardium would have resulted in uncontrolled hemorrhage. Instead, our method led to successful resuscitation of the patient until definitive care was available. A smaller pericardial incision than is traditionally used during ED thoracotomy deserves further consideration and research to determine whether and when it may be most useful as a temporizing treatment of cardiac tamponade when other methods have failed.

Modified Emergency Department Thoracotomy for Postablation Cardiac Tamponade
Annals of Emergency Medicine In Press – Full Text Available here from Annals site at time of blogging

More on needle thoracostomy for tension pneumothorax

Thanks to Dr. Matthew Oliver for highlighting these articles to me.
The standard teaching of placing a handy iv catheter in the 2nd intercostal space, midclavicular line for tension pneumothorax has been challenged by previous studies suggesting about a third of adults have a chest wall that is too thick for a standard 4.5 to 5 cm needle.
Some have therefore suggested that a lateral approach may be more appropriate.
Three studies this month provide more, although not entirely consistent, information.
An ultrasound study differed from previous CT studies by suggesting that most patients will have chest wall thickness (CWT) less than 4.5 cm, and found that the CW was thicker in the lateral area (4th intercostal space, midaxillary line)1.
In a cadaveric model, needle thoracostomy was successfully placed (confirmed by thoracotomy) in all attempts at the fifth intercostal space at the midaxillary line but in only just over half of insertions at the traditional second intercostal position2.
In a further study of trauma CT scans, measured CWT suggests that the lateral approach is less likely to be successful than the anterior approach, and the anterior approach may fail in many patients as well3.

The take home message for us must therefore remain that needle thoracostomy for tension pneumothorax might not be successful with a standard iv catheter, regardless of which approach is used. If tension pneumothorax is a possibility in the deteriorating patient and needle decompression has been unsuccessful, an alternative means of decompression (or ruling out pneumothorax) must be employed.

1. Ultrasound determination of chest wall thickness: implications for needle thoracostomy
Am J Emerg Med. 2011 Nov;29(9):1173-7
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Objective: Computed tomography measurements of chest wall thickness (CWT) suggest that standard- length angiocatheters (4.5 cm) may fail to decompress tension pneumothoraces. We used an alternative modality, ultrasound, to measure CWT. We correlated CWT with body mass index (BMI) and used national data to estimate the percentage of patients with CWT greater than 4.5 cm.

Methods: This was an observational, cross-sectional study of a convenience sample. We recorded standing height, weight, and sex. We measured CWT with ultrasound at the second intercostal space, midclavicular line and at the fourth intercostal space, midaxillary line on supine subjects. We correlated BMI (weight [in kilograms]/height2 [in square meters]) with CWT using linear regression. 95% Confidence intervals (CIs) assessed statistical significance. National Health and Nutrition Examination Survey results for 2007-2008 were combined to estimate national BMI adult measurements.

Results: Of 51 subjects, 33 (65%) were male and 18 (35%) were female. Mean anterior CWT (male, 2.1 cm; CI, 1.9-2.3; female, 2.3 cm; CI, 1.7-2.7), lateral CWT (male, 2.4 cm; CI, 2.1-2.6; female, 2.5 cm; CI 2.0-2.9), and BMI (male, 27.7; CI, 26.1-29.3; female, 30.0; CI, 25.8-34.2) did not differ by sex. Lateral CWT was greater than anterior CWT (0.2 cm; CI, 0.1-0.4; P < .01). Only one subject with a BMI of 48.2 had a CWT that exceeded 4.5 cm. Using national BMI estimates, less than 1% of the US population would be expected to have CWT greater than 4.5 cm.
Conclusions: Ultrasound measurements suggest that most patients will have CWT less than 4.5 cm and that CWT may not be the source of the high failure rate of needle decompression in tension pneumothorax.

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2. Anterior versus lateral needle decompression of tension pneumothorax: comparison by computed tomography chest wall measurement.
Acad Emerg Med. 2011 Oct;18(10):1022-6
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Objectives:  Recent research describes failed needle decompression in the anterior position. It has been hypothesized that a lateral approach may be more successful. The aim of this study was to identify the optimal site for needle decompression.

Methods:  A retrospective study was conducted of emergency department (ED) patients who underwent computed tomography (CT) of the chest as part of their evaluation for blunt trauma. A convenience sample of 159 patients was formed by reviewing consecutive scans of eligible patients. Six measurements from the skin surface to the pleural surface were made for each patient: anterior second intercostal space, lateral fourth intercostal space, and lateral fifth intercostal space on the left and right sides.

Results:  The distance from skin to pleura at the anterior second intercostal space averaged 46.3 mm on the right and 45.2 mm on the left. The distance at the midaxillary line in the fourth intercostal space was 63.7 mm on the right and 62.1 mm on the left. In the fifth intercostal space the distance was 53.8 mm on the right and 52.9 mm on the left. The distance of the anterior approach was statistically less when compared to both intercostal spaces (p <  0.01).
Conclusions:  With commonly available angiocatheters, the lateral approach is less likely to be successful than the anterior approach. The anterior approach may fail in many patients as well. Longer angiocatheters may increase the chances of decompression, but would also carry a higher risk of damage to surrounding vital structures.

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3. Optimal Positioning for Emergent Needle Thoracostomy: A Cadaver-Based Study
J Trauma. 2011 Nov;71(5):1099-1103/a>
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Background:  Needle thoracostomy is an emergent procedure designed to relieve tension pneumothorax. High failure rates because of the needle not penetrating into the thoracic cavity have been reported. Advanced Trauma Life Support guidelines recommend placement in the second intercostal space, midclavicular line using a 5-cm needle. The purpose of this study was to evaluate placement in the fifth intercostal space, midaxillary line, where tube thoracostomy is routinely performed. We hypothesized that this would result in a higher successful placement rate.

Methods:  Twenty randomly selected unpreserved adult cadavers were evaluated. A standard 14-gauge 5-cm needle was placed in both the fifth intercostal space at the midaxillary line and the traditional second intercostal space at the midclavicular line in both the right and left chest walls. The needles were secured and thoracotomy was then performed to assess penetration into the pleural cavity. The right and left sides were analyzed separately acting as their own controls for a total of 80 needles inserted into 20 cadavers. The thickness of the chest wall at the site of penetration was then measured for each entry position.

Results:  A total of 14 male and 6 female cadavers were studied. Overall, 100% (40 of 40) of needles placed in the fifth intercostal space and 57.5% (23 of 40) of the needles placed in the second intercostal space entered the chest cavity (p < 0.001); right chest: 100% versus 60.0% (p = 0.003) and left chest: 100% versus 55.0% (p = 0.001). Overall, the thickness of the chest wall was 3.5 cm ± 0.9 cm at the fifth intercostal space and 4.5 cm ± 1.1 cm at the second intercostal space (p < 0.001). Both right and left chest wall thicknesses were similar (right, 3.6 cm ± 1.0 cm vs. 4.5 cm ± 1.1 cm, p = 0.007; left, 3.5 ± 0.9 cm vs. 4.4 cm ± 1.1 cm, p = 0.008).
Conclusions:In a cadaveric model, needle thoracostomy was successfully placed in 100% of attempts at the fifth intercostal space but in only 58% at the traditional second intercostal position. On average, the chest wall was 1 cm thinner at this position and may improve successful needle placement. Live patient validation of these results is warranted.

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Update October 2012: See
this post about a further CT-scan based study favouring the 5th ICS compared with the 2nd

Tension pneumo treatment and chest wall thickness

An interesting ultrasound-based study challenges the assertion that a significant proportion of adults have a chest wall that is too thick for a standard iv cannula to reach the pleural space when attempting to decompress a tension pneumothorax. Perhaps there are other factors that make this technique so frequently ineffective.
The authors postulate that ultrasound measurements of chest wall thickness might be less than those obtained by CT scan due to the downward pressure on the tissues caused when the ultrasound transducer is placed on the chest, something that may also occur when a cannula is being pushed in, but would not be maintained after insertion of a cannula, perhaps leading to subsequent misplacement as the tissues recoil.
My view is that needle decompression might buy you time as a holding measure, but the patient with a tension pneumothorax will need a thoracostomy sooner rather than later.


Objective: Computed tomography measurements of chest wall thickness (CWT) suggest that standard- length angiocatheters (4.5 cm) may fail to decompress tension pneumothoraces. We used an alternative modality, ultrasound, to measure CWT. We correlated CWT with body mass index (BMI) and used national data to estimate the percentage of patients with CWT greater than 4.5 cm.

Methods: This was an observational, cross-sectional study of a convenience sample. We recorded standing height, weight, and sex. We measured CWT with ultrasound at the second intercostal space, midclavicular line and at the fourth intercostal space, midaxillary line on supine subjects. We correlated BMI (weight [in kilograms]/height2 [in square meters]) with CWT using linear regression. 95% Confidence intervals (CIs) assessed statistical significance. National Health and Nutrition Examination Survey results for 2007-2008 were combined to estimate national BMI adult measurements.

Results: Of 51 subjects, 33 (65%) were male and 18 (35%) were female. Mean anterior CWT (male, 2.1 cm; CI, 1.9-2.3; female, 2.3 cm; CI, 1.7-2.7), lateral CWT (male, 2.4 cm; CI, 2.1-2.6; female, 2.5 cm; CI 2.0-2.9), and BMI (male, 27.7; CI, 26.1-29.3; female, 30.0; CI, 25.8-34.2) did not differ by sex. Lateral CWT was greater than anterior CWT (0.2 cm; CI, 0.1-0.4; P <.01). Only one subject with a BMI of 48.2 had a CWT that exceeded 4.5 cm. Using national BMI estimates, less than 1% of the US population would be expected to have CWT greater than 4.5 cm.
Conclusions: Ultrasound measurements suggest that most patients will have CWT less than 4.5 cm and that CWT may not be the source of the high failure rate of needle decompression in tension pneumothorax.

Ultrasound determination of chest wall thickness: implications for needle thoracostomy

Am J Emerg Med. 2011 Nov;29(9):1173-7

Saving Lives Through Failure

Think about what you would do if faced with the following situation:

You sedate and paralyse a patient with severe injuries in order to intubate them. You are unable to intubate due to a poor view and massive orofacial haemorrhage. An iGel provides temporary oxygenation while you prepare for a surgical airway.

Your first surgical airway attempt fails due to insertion of the bougie through a false (too superficial) passage. You spot your mistake and re-do the procedure successfully with a deeper incision. The patient’s airway is secure and there is good oxygenation and ventilation.

You discover that a colleague has videoed the procedure on his iPhone. However he only captured the first, unsuccessful attempt. The patient is not identifiable in the close up video. It’s late at night and only he and you know of the existence of the video. He asks you what you want him to do with it.



Do you…
(a) Ask your colleague to delete the video?
(b) Watch the video with him and look for learning points, and then delete it?
(c) Ask him for a copy of it and request that he doesn’t show it to anyone else?
(d) Other course of action
Consider your course of action given this situation, and then click below to reveal what my colleague did recently in exactly the same scenario…
[EXPAND What did he do?]
(d) He did something else entirely: he got a copy of the video, burned it onto a CD, and left it on his boss’s desk!

It takes a certain kind of practitioner to risk embarrassment and criticism in the pursuit of the greater educational good.

He had already ascertained what he would need to do differently next time, so had nothing personal to gain from his chosen action.

Instead, he believed that sharing the video would help prevent his colleagues from repeating the same mistake, and help his supervisors review their cricothyroidotomy training in order to better prepare their team for the procedure. Ultimately, this gesture was directed towards the good of our patients.

His actions may have saved more than one life that evening.

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Needle versus mini-chest tube for pneumothorax

A mini-chest tube with Heimlich valve was an alternative to needle aspiration in patients with spontaneous pneumothorax, with some apparently favourable outcomes in this small study. The authors do not specify what type of chest tube they used but report it was 12 Fr diameter. They highlight an interesting difference in guidelines for the treatment of spontaneous primary pneumothorax:
Traditional preference has been for chest tube insertion and admission to the ward. British Thoracic Society recommends needle aspiration (NA) as the initial treatment of choice, but American College of Chest Physicians Consensus prefers insertion of small-bore catheters (≤14F) or chest tubes (16-22F).


OBJECTIVES: The aim of this study was to compare outcomes and complications associated with needle aspiration (NA) and minichest tube (MCT) insertion with Heimlich valve attachment in the treatment of primary spontaneous pneumothorax at an emergency department (ED).

METHODS: Patients presenting with primary spontaneous pneumothorax were randomized to NA or MCT. They had repeat chest x-rays immediately after the procedure and 6 hours later. Patients who underwent NA were discharged if repeat x-rays showed less than 10% pneumothorax. Those who had MCT were discharged if repeat x-rays did not show worsening of pneumothorax. They were reviewed at the outpatient clinic within 3 days. The primary outcomes of interest were failure rate and admission rate. The secondary outcomes were complication rate, pain and satisfaction scores, length of hospital stay, and rate of full recovery during outpatient follow-up.

RESULTS: There were 48 patients whose mean age was 25 years. We found no difference in failure rate between the groups, except that there were more MCT (24%) than NA patients (4%) with complete expansion at first review (difference, -0.20; 95% confidence interval, -0.38 to -0.01). Thirty-five percent of NA group and 20% of MCT group needed another procedure at the ED. Fifty-two percent of NA patients and 28% of MCT patients were admitted from the ED to the inpatient ward. Nine percent and 12%, respectively, of patients who had NA and MCT were admitted from the review clinic. Both groups of patients had equivalent pain scores, satisfaction scores, and complication rates.

CONCLUSION: Both MCT and NA allowed safe management of primary spontaneous pneumothorax in the outpatient setting.

A randomized controlled trial comparing minichest tube and needle aspiration in outpatient management of primary spontaneous pneumothorax
Am J Emerg Med. 2011 Nov;29(9):1152-7

AF in sepsis and risk of stroke

Atrial fibrillation can occur in the setting of severe sepsis, and often presents a therapeutic conundrum for critical care physicians, in that it can be relatively resistant to treatment until the sepsis has resolved, and its prognostic significance is unclear. A new study on a massive dataset shows atrial fibrillation in the setting of severe sepsis is associated with an increased risk of stroke and increased hospital mortality. Patients with severe sepsis who developed new-onset AF had a greater risk of in-hospital stroke than patients with preexisting AF and individuals without a history of AF.


Context New-onset atrial fibrillation (AF) has been reported in 6% to 20% of patients with severe sepsis. Chronic AF is a known risk factor for stroke and death, but the clinical significance of new-onset AF in the setting of severe sepsis is uncertain.

Objective To determine the in-hospital stroke and in-hospital mortality risks associated with new-onset AF in patients with severe sepsis.

Design and Setting Retrospective population-based cohort of California State Inpatient Database administrative claims data from nonfederal acute care hospitals for January 1 through December 31, 2007.

Patients Data were available for 3 144 787 hospitalized adults. Severe sepsis (n = 49 082 [1.56%]) was defined by validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 995.92. New-onset AF was defined as AF that occurred during the hospital stay, after excluding AF cases present at admission.

Main Outcome Measures A priori outcome measures were in-hospital ischemic stroke (ICD-9-CM codes 433, 434, or 436) and mortality.

Results Patients with severe sepsis were a mean age of 69 (SD, 16) years and 48% were women. New-onset AF occurred in 5.9% of patients with severe sepsis vs 0.65% of patients without severe sepsis (multivariable-adjusted odds ratio [OR], 6.82; 95% CI, 6.54-7.11; P < .001). Severe sepsis was present in 14% of all new-onset AF in hospitalized adults. Compared with severe sepsis patients without new-onset AF, patients with new-onset AF during severe sepsis had greater risks of in-hospital stroke (75/2896 [2.6%] vs 306/46 186 [0.6%] strokes; adjusted OR, 2.70; 95% CI, 2.05-3.57; P < .001) and in-hospital mortality (1629 [56%] vs 18 027 [39%] deaths; adjusted relative risk, 1.07; 95% CI, 1.04-1.11; P < .001). Findings were robust across 2 definitions of severe sepsis, multiple methods of addressing confounding, and multiple sensitivity analyses.
Conclusion Among patients with severe sepsis, patients with new-onset AF were at increased risk of in-hospital stroke and death compared with patients with no AF and patients with preexisting AF.

Incident Stroke and Mortality Associated With New-Onset Atrial Fibrillation in Patients Hospitalized With Severe Sepsis
JAMA. 2011 Nov 13. [Epub ahead of print]

AMI mortality increased as the number of risk factors declined


An interesting finding: in patients with myocardial infarction, hospital mortality increased consistently as the number of risk factors declined. There was also an inverse relationship between age and the number of coronary heart disease risk factors.
The authors discuss the possibility that the some of the zero risk factor group may have had risk factors unknown to the patient or not reported in the history, or may have had other factors that influence the disease, for example insulin resistance, abdominal obesity, psychosocial factors, poor nutrition, or physical inactivity.


Context Few studies have examined the association between the number of coronary heart disease risk factors and outcomes of acute myocardial infarction in community practice.

Objective To determine the association between the number of coronary heart disease risk factors in patients with first myocardial infarction and hospital mortality.

Design Observational study from the National Registry of Myocardial Infarction, 1994-2006.

Patients We examined the presence and absence of 5 major traditional coronary heart disease risk factors (hypertension, smoking, dyslipidemia, diabetes, and family history of coronary heart disease) and hospital mortality among 542 008 patients with first myocardial infarction and without prior cardiovascular disease.

Main Outcome Measure All-cause in-hospital mortality.

Results A majority (85.6%) of patients who presented with initial myocardial infarction had at least 1 of the 5 coronary heart disease risk factors, and 14.4% had none of the 5 risk factors. Age varied inversely with the number of coronary heart disease risk factors, from a mean age of 71.5 years with 0 risk factors to 56.7 years with 5 risk factors (P for trend < .001). The total number of in-hospital deaths for all causes was 50 788. Unadjusted in-hospital mortality rates were 14.9%, 10.9%, 7.9%, 5.3%, 4.2%, and 3.6% for patients with 0, 1, 2, 3, 4, and 5 risk factors, respectively. After adjusting for age and other clinical factors, there was an inverse association between the number of coronary heart disease risk factors and hospital mortality adjusted odds ratio (1.54; 95% CI, 1.23-1.94) among individuals with 0 vs 5 risk factors. This association was consistent among several age strata and important patient subgroups.
Conclusion Among patients with incident acute myocardial infarction without prior cardiovascular disease, in-hospital mortality was inversely related to the number of coronary heart disease risk factors.

Number of Coronary Heart Disease Risk Factors and Mortality in Patients With First Myocardial Infarction
JAMA. 2011;306(19):2158-2159