Most patients with acute myocarditis and mild cardiac involvement recover without long-term sequelae. However, those patients with advanced cardiac involvement may have a more varied outlook. Of these, at least one-third of patients will have residual ventricular dysfunction, around 25% will progress to transplantation or death, and the remainder will recover and have normal ventricular function.1,2
Various diagnostic tests are used to assess heart function, but a test that predicts the prognosis of heart failure and thereafter helps clinicians to intervene earlier in those patients with a poor prognosis is still lacking.3 Cardiac power index (CPI) (mean arterial blood pressure x cardiac index x 0.0022) has been demonstrated to be an important haemodynamic predictor of mortality and adverse events in patients with various cardiac diseases.4-9 However, its prognostic impact on patients with inflammatory cardiomyopathy is less well investigated.
All patients with biopsy-proven inflammatory cardiomyopathy undergoing invasive haemodynamic assessment with longitudinal follow-up were retrospectively analysed and classified into two groups. Group 1 represented patients with a normal CPI (≥0.5 W/m²) and Group 2 represented patients with a diminished CPI (<0.5 W/m²). The combined primary endpoint was cardiac death, aborted sudden cardiac death, heart transplantation, and left ventricular assist device implantation.
One hundred and sixty-seven patients (mean age: 60±11 years; 71% male) were available for analysis and the mean CPI was 0.43±0.14 W/m2 (Group 1: 0.62±0.12 W/m2 versus Group 2: 0.37±0.083 W/m2; p<0.001). At presentation, a lower CPI was associated with lower systolic, diastolic, and mean blood pressure; lower ejection fraction; lower cardiac output; higher pulmonary vascular resistance; and higher right ventricular pressure.
Over a mean of 3.6±2.4 years of follow-up, there were 7 deaths, 12 incidences of aborted sudden cardiac death, 3 transplants, and 2 left ventricular assist device placements. Diminished CPI was associated with an increased incidence of the combined primary endpoint (hazard ratio: 3.4; 95% confidence interval: 1.29–8.98). Event-free survival by Kaplan–Meier estimate was significantly lower in Group 2 than Group 1 (80.1% versus 97.4%, respectively; p<0.01).
In conclusion, patients with inflammatory cardiomyopathy and a low CPI had an increased incidence of the combined primary endpoint during long-term follow-up compared to patients with a normal CPI.