Differentiating the mimickers of acute pericarditis/myopericarditis

Dear Sir, We thank you for the opportunity to reply to the insightful comments on our article: ‘ECG Spot Diagnosis: Acute Pericarditis’ (AP).1 In the presence of an elevated troponin, the academically correct term would be acute myopericarditis (MP). However, in the absence of global or regional impairment of left ventricular function on transthoracic echocardiography (TTE) in MP, definitive confirmation of myocardial involvement would require endomyocardial biopsy.2 This is not routinely practiced or recommended given the overall good prognosis of MP in the absence of heart failure symptoms.2,3 The typical ECG changes described in our case report are commonly seen in AP from any cause. They in fact represent inflammation of the epicardium as the parietal pericardium is electrically inert.4 As such, PR-segment depression in the inferior leads and/or precordial leads, particularly V5 and V6, commonly occurs in AP and is not limited to MP.5 It is a highly specific finding for AP that is frequently overlooked.5 Although takotsubo cardiomyopathy (TTC) and early pericarditis secondary to acute myocardial infarction (AMI) may share certain similar ECG features with AP/MP; useful differentiating characteristics include a prolonged QTc interval, present in almost 50% of TTC cases,6 and Q-waves within a single coronary territory in pericarditis secondary to AMI. The respondent’s suggested proposal of a blanket approach to emergency TTE in those presenting with a suspected ST-segment elevation AMI would unnecessarily delay the time to reperfusion of the infarct related artery. Importantly, when the diagnosis is uncertain, emergency TTE before coronary angiography is recommended by recent guidelines.7 However, routine TTE that delays emergency angiography is not recommended and may cause harm.7 Careful clinical judgment, rather than a ‘one fits all’ policy, in the setting of ST elevation must therefore guide decision making in the acute setting. Conflict of interest: None declared.