Coronary artery disease: Primary care and prevention – 2
Check for differential diagnosis
Some of the important differential diagnosis in the case of acute coronary syndrome are acute pulmonary embolism, aortic dissection, pneumothorax, esophageal disease, perforated peptic ulcer, cholecystitis, gastritis and sometimes even Herpes Zoster of left thoracic region in pre-eruptive phase. A good history, physical findings and sometimes time are needed for an accurate differential diagnosis. Checking for asymmetry of peripheral pulses is often resorted to for excluding aortic dissection, though it may still miss an aortic dissection sparing the branches as in descending thoracic aortic dissection. Missing a differential diagnosis can sometimes be catastrophic. Sometimes differential diagnosis may co-exist with acute coronary syndrome – aortic dissection may be complicated by inferior wall infarction as the dissection flap involves the ostium of right coronary artery. Pneumothorax can be associated with some ECG changes due to the shift of the heart and hemodynamic compromise may be mistaken for cardiogenic shock. Chest X-ray, preferably in erect posture is useful in pneumothorax and perforated peptic ulcer and to some extent in aortic dissection and pulmonary embolism. CT triple rule out is often considered in the emergency department for checking pulmonary embolism, aortic dissection and proximal coronary artery disease.
Aspirin and nitrate as initial treatment
Non enteric coated aspirin, to be chewed for buccal absorption and rapid action, is the first drug to be given in suspected acute coronary syndrome. Sublingual nitrates can be used for pain relief, but hospitalise if there is no relief in 5 minutes or if there is worsening. Watch for a rane instance of syncope with initial use of nitrates, especially if the subject walks with a tablet under the tongue. It is always wise to exclude recent use of phosphodiesterase inhibitor sildenafil as nitrate use in these individuals can cause severe hypotension.
Transfer to hospital
It is preferable to transfer a patient with acute coronary syndrome in an ambulance. There is one in 300 chance to develop cardiac arrest en route, which can be better tackled in an ambulance. It has been shown that those who arrive in an ambulance receive earlier reperfusion in the hospital. Pre hospital ECG in the ambulance can be very useful in improving time to reperfusion (even pre-hospital thrombolysis) and preferential transport to PCI (percutaneous coronary intervention) capable centre in case of STEMI is possible. The PCI centre can be informed en route so that the cath lab can be ready at arrival, permitting bypass of the emergency department, thereby improving door to balloon time in case of PCI. It is to be noted that self driven vehicle is never to used in acute coronary syndrome.