Here the elderly man presents with classical ischemic chest pain. This would be considered tobe an Acute coronary syndrome until proven otherwise.
Look at the ECG which reveals the Presence of Left bundle branch block ,Resulting in diagnostic conundrum.
Recently, American heart association recommends that patients with suspected ischemia ,and new or presumably new LBBB be considered as having STEMI.
However, STEMI guidelines of AHA no longer recommend this, possibly because coronary angiography has shown that only between 14-44% of such patients has acute arterial occlusion.
This is diagnostic dilemma, although majority of patients do not have an acute MI, a non significant percentage of them do. As withholding Reperfusion therapy to this population maybe potentially lethal, So what's the Option?
Fortunately, There exist several diagnostic tools which can be used accurately identify the patients presenting with LBBB who do have acute coronary occlusion. The Sgarbossa ECG criteria are most validated For these.
Sgarbossa consist of three criteria ,For diagnosing this patient Consider the first Sgarbossa criterion i.e. ST SEGMENT ELEVATIONS > or equal to 1mm Concordant with the QRS complex in any leads.
One Charecteristic of an uncomplicated LBBB is the presence of ST -T discordance, in other words, If the QRS complex is mainly directed upwards (As in lateral leads), The ST segment will be depressed, and T wave inverted. Conversely if the QRS vector is mainly directed downwards the ST segment will be elevated and TSH wave prominently Positive.
Loss of Charecteristic pattern i.e. the QRS complex and ST-T segment and T wave all being concordant is strongly specific for acute MI. Note that this is present in this patient .
While Cardiac TROPONIN are highly specific for Myocardial injury, and are the prefered biomarkers for diagnosis of MI, it should be appreciated that these are ideally estimated atleast 6 hours following the symptoms onset. Assays performed earlier maybe misleadingly low.
In addition while acute ECHOCARDIOGRAM may demonstrate the Segmental Hypokinesis supportive of an Acute MI. This not essential in presence of definitive ELECTROCARDIOGRAPHIC DIAGNOSIS and should never delay the Reperfusion therapy.
Note that Chest X-ray maybe Rapidly performed in Emergency department and is Routinely recommended in all patients with chest pain.This is to exclude the aortic dissection,Which itself can give rise secondary MI.
Antacids, placement of NG tube, aortic surgery are not indicated in this Patient.
References : Am fam physician, 2012-21,Diagnosing the cause of Chest pain .Cayley WE Jr.
•• Am Fam physician 1,72(1):119-26 .Diagnosis of acute coronary syndrome .Achar SA, Kundu S, Norcross WA.
•• Med J Aust .2013 Jul 8, 199(1):30-4 .The approach to patient with possible cardiac chest pain .Parsonage WA, Chullen L, Younger JF.