PR segment depression and PR-ST dissociation
PR segment depression can occur in pericarditis and atrial infarction. Dissociation between PR and ST segments (PR-ST dissociation) can occur in pericarditis.
In inferior wall infarction with which atrial infarction is usually associated, there can be ST elevation and PR depression in inferior leads. Jim MH et evaluated the prognostic implication of PR segment depression in inferior leads in acute inferior wall infarction . They noted profound PR segment depression (1.2 mm or more) in 9 of 463 consecutive patients presenting with inferior wall myocardial infarction. They noted that patients with atrial ischemia as indicated by PR segment depression tended to present earlier and had a higher frequency of first degree AV block and supraventricular arrhythmias. They noted higher incidence of cardiac free wall rupture and in hospital mortality, which had a high statistical significance – p=0.001 and 0.015 respectively. Lu ML and colleagues found that PR segment depression in inferior leads was associated with increased one year mortality patients with ST elevation myocardial infarction .
PR segment depression was noted in 45.5% of 79 patients with pericardial disease referred for surgery . They noted that PR segment depression was associated with elevated inflammatory markers, purulent content of pericardial fluid, calcification, features of compression – either tamponade or constriction, arrhythmias and unfavourable outcome.
Asymptomatic pericardial effusion can also be associated with PR segment depression according to Kudo Y et al . PR segment depression was noted in 40 of their 176 asymptomatic patients referred for echocardiography. ST elevation was noted in 8 of these patients (PR-ST dissociation).
Jim MH et al. Prognostic implications of PR-segment depression in inferior leads in acute inferior myocardial infarction. Clin Cardiol. 2006 Aug;29(8):363-8.
Lu ML et al. Prognostic significance of abnormal P wave morphology and PR-segment displacement after ST-elevation myocardial infarction. Int J Cardiol. 2015 Oct 15;197:216-21.
Kudaiberdiev T et al. Electrocardiographic abnormalities in patients with pericardial disease–Association of PR segment depression with arrhythmias and clinical signs: Experience of cardiac surgery center. J Electrocardiol. 2016 Jan-Feb;49(1):29-36.
Kudo Y et al. Clinical correlates of PR-segment depression in asymptomatic patients with pericardial effusion. J Am Coll Cardiol. 2002 Jun 19;39(12):2000-4.