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Three Part Question

In [patients undergoing coronary angiography] [for acute myocardial infarct] [what is the prevalence of angiographically normal coronary arteries]?

Clinical Scenario

A 56-year-old female presents to the emergency department complaining of intermittent nausea, she is now also experiencing angina, dyspnea, and diaphoresis. EKG shows signs concerning for myocardial ischemia. Interventional cardiology prepares to take the patient to the cardiac suite for coronary angiography.

Search Strategy

Medline 1996-04/13 using OVID interface, Cochrane Library (2013), PubMed clinical queries
[(exp myocardial infarction) AND (exp coronary angiography) AND (normal coronary arteries. mp OR MINCA.mp)] Limit to English language

Search Outcome

154 papers were identified; of which 4 trials answered the clinical question

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Agewall S. Daniel M. Eurenius L. Ekenback C. Skeppholm M. Malmqvist K. Hofman-Bang C. Collste O. Fri October 2012 Sweden	All patients with a final diagnosis of MI below the age of 70 were registered within the 3 month study period.	This is an observational study. This study is unique because this cohort includes only patients with a final diagnosis of MI.	Patients suffering MI with angiographically normal coronary arteries defined as completely normal or mild atheromatosis.	Of 152 patients found to have MI, 11 or 7.2% were found to have normal coronary arteries.	1. Not all patients with MI underwent coronary angiography. 2. This is a small pilot study. 3. Actual prevalence is not reported in a straight forward manner.
Widimsky P. Stellova B. Groch L. Aschermann M. Branny M. Zelizko M. Stasek J. Formanek P. November 2006	Data comes from patients enrolled in the PRAGUE 1 and PRAGUE 2 studies along with a simultaneous registry of acute STEMI patients. The combined data includes 1150 patients with suspected acute ST elevation MI, of these, 1004 underwent angiography within 2 hours of initial EKG or while in the acute ST phase of suspected MI.	This is an observational study.	Number of patients with suspected MI found to have normal coronary arteries.	Normal coronary angiograms were obtained in 26 out of the 1004 patients, or 2.6%.	Not all patients registered in the PRAGUE studies were included in this study. Although all PRAGUE patients were diagnosed with STEMI, only those patients undergoing coronary angiography within 2 hours of initial EKG were included in this study.
Stensaeth KH. Fossum E. Hoffmann P. Mangschau A. Klow NE. March 2011 Norway	All patients 18-75 years old with chest pain less than 24 hours and significant ST elevation or new LBBB and completely normal coronary arteries on angiograghy were included in this prospective registry.	This is a prospective series registry of STEMI Patients with normal coronary arteries. This cohort of patients then underwent Cardiac Magnetic Resonance Imaging (CMR) to further define the potential role of CMR in differential diagnosis of patients with suspected STEMI and normal coronary arteries.	Number of patients with suspected MI found to have completely normal coronary arteries.	49 of 1145 or 4.3% of suspected STEMI patients had completely normal coronary arteries.	This study was not designed to characterize the incidence of STEMI patients with normal coronary arteries however data needed to answer our clinical question was available in the cohort description. This study may be too strict in defining normal coronary arteries.
Larsen AI. Galbraith PD. Ghali WA. Norris CM. Graham MM. Knudtson ML January 15, 2005 Canada	This study included all adult patients undergoing cardiac catheterization in Alberta Canada from January 1995 to December 2000 with AMI listed as the indication for the procedure.	The Alberta Provincial Project of Outcome Assessment in Coronary Heart Disease is a clinical data collection initiative of prospectively compiled data.	Number of patients with suspected MI found to have normal coronary arteries.	273 of 9796 or 2.8% were found to have normal coronary arteries. (95% CI 2.5-3.1). They also noted 452 of the 9796 or 4.6% had only mild disease defined as less than 50% lesions.

Comment(s)

Interest in the prevalence of normal coronary arteries in the setting of suspected AMI has increased in the past several years as the use of angiography has grown substantially. Of the four papers used in this BET, three studies directly answered our clinical question. These papers included all patients undergoing angiography with suspected AMI. Patients were included even if they were later given an alternate final diagnosis. These studies also used more stringent definitions of normal coronary arteries and reported prevalence between 2.6% and 4.3%. One of these three papers provides a bridge to understanding the higher prevalence reported in the outlying 4th study. Larsen et al. reported prevalence of completely normal coronary arteries at 2.8%. They also reported the number of those patients found to have less than 50% lesions. When the completely normal and mild disease groups are combined as was done in the more liberal definition used in the remaining study; then prevalence would be 7.4% versus 2.8%. The remaining study used the more permissive definition of normal coronary arteries. Agewall et al. included patients with mild atheromatosis less than 50% in their definition of normal coronary arteries. Additionally patients were only included if the final diagnosis was MI. Prevalence of 7.2% was reported in this study.

Clinical Bottom Line

In patients undergoing coronary angiography for suspected acute myocardial infarction the prevalence of those found to have normal coronary arteries is between 2.6% and 7.4%.

References

1. Agewall S. Daniel M. Eurenius L. Ekenback C. Skeppholm M. Malmqvist K. Hofman-Bang C. Collste O. Frick M. Henareh L. Jernberg T. Tornvall P Risk factors for myocardial infarction with normal coronary arteries and myocarditis compared with myocardial infarction with coronary artery stenosis. Angiology Oct 2012; 500-503
2. Widimsky P. Stellova B. Groch L. Aschermann M. Branny M. Zelizko M. Stasek J. Formanek P. Prevalence of normal coronary angiography in the acute phase of suspected ST-elevation myocardial infarction: experience from the PRAGUE studies. Canadian Journal of Cardiology November 2006; 1147-1152
3. Stensaeth KH. Fossum E. Hoffmann P. Mangschau A. Klow NE. Clinical characteristics and role of early cardiac magnetic resonance imaging in patients with suspected ST-elevation myocardial infarction and normal coronary arteries. The International Journal of Cardiovascular Imaging March 2011; 355-365
4. Larsen AI. Galbraith PD. Ghali WA. Norris CM. Graham MM. Knudtson ML Characteristics and outcomes of patients with acute myocardial infarction and angiographically normal coronary arteries. American Journal of Cardiology January 15 2005; 261-263