Clinical significance of myocardial involvement in acute idiopathic pericarditis

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.

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.

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.

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.