Clinical significance of myocardial involvement in acute idiopathic pericarditis

BACKGROUND: Acute idiopathic pericarditis (AIP) is frequently accompanied by myocardial involvement (AIPM). Although in acute myocarditis, the myocardial inflammation can lead to life-threatening complications, the outcome of patients with AIPM has been described as good. It remains unclear if a good prognosis of patients with AIPM reflects mild myocardial involvement or good medical management. METHODS: A retrospective analysis of life-threatening complications and life-saving interventions in a cohort of 248 consecutive patients admitted to a single medical center between 2006 and 2017 with AIP (n = 169) or AIPM (n = 79). Major adverse cardiac events (MACE) included cardiac tamponade, cardiogenic shock, ventricular tachycardia, pericardiocentesis, pericardiectomy, large pericardial effusion and death. RESULTS: Patients with AIPM were younger than patients with AIP (p < 0.001), and more often had left ventricular dysfunction (31.6% vs. 1.2%, p < 0.001) and less often had large pericardial effusion (1.3% vs. 13.6%, p = 0.002), and MACE (5.1% vs. 14.8%, p = 0.014). Cardiac tamponade occurred in 5.3% of the patients with AIP as opposed to 1.3% of the patients with AIPM (p = 0.176). Severe left ventricular dysfunction with cardiogenic shock occurred exclusively among patients with AIPM but the rate was low (2.5%). Life-saving interventions were used in both groups at comparable rates (2.5% vs. 5.3%, p = 0.510). There were no in-hospital deaths. CONCLUSIONS: Myocardial involvement in acute pericarditis is associated with a low rate of severe left ventricular dysfunction and cardiogenic shock and a reduced rate of large pericardial effusion, resulting in a lower rate of MACE. Life-saving interventions were used at comparable rates in patients with and without myocardial involvement having excellent survival rates.