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Giant cell versus lymphocytic myocarditis. A comparison of their clinical features and long-term outcomes
R Davidoff1, I Palacios, J Southern
1Evans Memorial Department of Clinical Research, Boston University Medical Center, Mass.
Insights
Giant cell myocarditis, though rare, is linked to ventricular tachycardia and pacemaker needs. Patients with giant cell myocarditis face a higher risk of adverse cardiovascular events compared to those with lymphocytic myocarditis.
Area of Science:
- Cardiology
- Pathology
Background:
- Giant cell myocarditis (GCM) is a rare cardiac condition with limited premortem diagnostic data and unknown natural history.
- No prior studies have directly compared GCM with lymphocytic myocarditis (LCM).
Purpose of the Study:
- To compare the clinical features, cardiac function changes, and outcomes of patients diagnosed with GCM versus LCM.
Main Methods:
- Retrospective evaluation of clinical data, left ventricular ejection fraction (LVEF) changes, and outcomes in patients with histologically confirmed myocarditis.
- Patients were categorized into GCM (n=10) and LCM (n=36) groups.
Main Results:
- GCM patients showed significantly higher rates of ventricular tachycardia (90% vs. 25%) and atrioventricular block requiring pacemakers (60% vs. 8.3%).
- Left ventricular systolic function declined in GCM patients (LVEF change: -0.17) but improved in LCM patients (LVEF change: +0.07).
- GCM was associated with a greater proportion of adverse events (death or transplantation) (p=0.03), despite similar 4-year survival rates.
Conclusions:
- Giant cell myocarditis is more common than previously thought and strongly associated with ventricular tachycardia and pacemaker dependence.
- Patients with GCM have a significantly higher likelihood of adverse cardiovascular events, possibly due to progressive left ventricular systolic dysfunction.
Background:
Giant cell myocarditis has rarely been diagnosed premortem, and little is known about its natural history. In addition, no comparative studies with lymphocytic myocarditis exist.
Methods And Results:
The clinical features, serial change in left ventricular fraction (LVEF), and outcomes of all patients with histologically verified myocarditis were retrospectively evaluated. Ten patients (22%) were found to have giant cell myocarditis (group 1), whereas the remaining 36 (78%) had lymphocytic myocarditis (group 2). Age at presentation, gender distribution, duration of symptoms, initial LVEF, and resting hemodynamics did not differ between groups. Ventricular tachycardia was detected in 90% of group 1 patients compared with only 25% of group 2 (p = 0.0007). Atrioventricular block that required pacemaker insertion was also more common in group 1 (60%) than in group 2 (8.3%) (p = 0.001). Left ventricular systolic function declined during follow-up in group 1 patients (LVEF, 0.43 +/- 0.07-0.26 +/- 0.05, p = 0.11) but increased in group 2 patients (LVEF, 0.33 +/- 0.03-0.41 +/- 0.03, p = 0.02). When the net change between initial and final LVEF was assessed, a significant difference was evident (giant cell group, -0.17 +/- 0.06; lymphocytic group, +0.07 +/- 0.03; p = 0.0008). Although a greater proportion of patients in group 1 died or required transplantation (seven of 10 versus 11 of 36, p = 0.03), actuarial survival over 4 years was not different for the giant cell group (50%) than for the lymphocytic group (62%).
Conclusion:
Giant cell myocarditis was more prevalent than previously recognized and highly associated with both ventricular tachycardia and pacemaker requirement. The likelihood of an adverse event, either cardiovascular mortality or cardiac transplantation, was significantly greater for patients with giant cell myocarditis than for those with lymphocytic myocarditis, perhaps because of the progressive decline in left ventricular systolic function that was observed in those with giant cell myocarditis.