Afterload mismatch is associated with gender mismatch and negatively affect long-term outcome after heart transplant

Cardiac physiology changes after heart transplant (HT), resulting in a restrictive physiology with an increase in both arterial elastance (Ea) and ventricular elastance (Ees). This leads to a higher susceptibility to develop afterload mismatch, although the early identification of this phenomenon has not yet been explored. The aim of this study is to identify the presence of afterload mismatch after HT, its determinants, and its impact on cardiac mortality.

We conducted an observational, single-centre study based on the historical cohort of patients who underwent HT from 1985 to 2015 at our institution. We included patients who had survived the first year after HT with left ventricular ejection fraction (LVEF) ≥ 50%, International Society of Heart and Lung Transplantation (ISHLT) cardiac allograft vasculopathy of grade 0-1, and ISHLT acute cellular rejection of grade 0-1R at 1 year after HT. Ea and Ees were calculated using a non-invasive method based on blood pressure and end-systolic volume and end-diastolic volume measured at transthoracic echocardiography. Patients were grouped in 3 categories according to the presence of increased afterload and afterload mismatch as follows: low afterload (LA - Ea lower the median), matched high afterload (MHA - Ea higher of equal than the median, Ees higher or equal than the median), afterload mismatch (AM - Ea higher or equal than the median, Ees lower than the median). The impact of AM on long-term outcome, defined as cardiac mortality, was investigated, as well as predictors of AM.

The study cohort consisted of 345 HT patients. The median of Ea and Ees were 4.0mmHg/mL and 6.75mmHg/mL, respectively. 49 patients (13%) developed AM, while LA and MHA groups accounted for 49% and 36% of the cohort, respectively. Patients with AM were mostly male (91%), with ischemic heart disease (45%) and a higher percentage of left ventricular assisted device prior to HT (8%). LVEF was lower in AM (57% vs 63% and 64% for LA and MHA respectively, p < 0.0001), while stroke volume was lower than LA and similar to MHA (27ml vs 35mL and 26mL for LA and MHA respectively, p = 0.0001). Predictors of AM were male recipient from male donor (Mr/Md) (β 015, p = 0.0067) and Mr from female donor (Mr/Fd) (β 0.6, p = 0.0078). After a median of 11.3-year follow-up, 59 (17%) HT recipients died. Cardiac mortality was higher in AM than in the other groups (AM median survival 17.2y vs 27.8y and 24.1y for LA and MHA respectively, log-rank p = 0.005). After adjusting for confounding variables, AM was a predictor of cardiac mortality (HR: 2.26; 95%CI 1.18 – 4.35), such as Mr/Fd (HR 2.94; 95%CI 1.18 – 4.35, p = 0.0358).