Coronary artery calcium score progression in heart transplant patients

The coronary artery calcium score(CACS) is a well-established marker of coronary atherosclerosis with absence of CAC indicating a low likelihood of obstructive coronary artery disease and a low risk of major adverse events. While CACS has been extensively studied in general populations, limited research has focused on its progression and clinical implications in heart transplant(HT) recipients.

We aimed to evaluate the progression of CACS in HT patients during long-term follow-up on computed tomography(CT).

We included all HT recipients who underwent CT scans during annual checkup since 2018. If a stent was present in a coronary artery before baseline CT, that artery was excluded from the CACS for the entire follow-up period(FUP). For patients who received stents during the FUP, their CACS was included up to the time of stent placement.

Patients were categorized into 2 groups based on CACS over a 5-year FUP: (1)a stable CACS of 0 throughout FUP and (2)any progression of CACS during FUP. Baseline characteristics were extracted from the electronic patient database and compared between the groups.

To evaluate changes in CACS over time, we used Generalized Linear Mixed Models(GLMM) with time as a continuous variable. In this model, patients with a stable CACS of 0 were excluded from analysis to focus on those with measurable CACS progression.

We included 116 HT patients (median age at transplant: 42[IQR25-52] years; 62% male. Median time between HT and first CT was 9[IQR7-13] years. Of the total cohort, 44% of patients were classified into group 1 and 56% of patients into group 2. Baseline characteristics are shown in Table 1.

The median CACS in the total cohort increased from 0[0-36] at baseline to 3[0-178] at year 5, Figure 1. The proportion of patients with a CACS of 0 decreased from 56% at baseline to 48% at year 5 (p<0.001).

Among patients with any CACS progression (excluding those with CACS=0), the median CACS increased from 25[1-123] at baseline to 161[36-323] at year 5. In a GLMM, the CACS increased significantly over time, with an annual log(CAC+1) increase of 0.437(95%CI0.383–0.491; p<0.001), corresponding to a 55% yearly relative increase. In a GLMM including age and time, there was a significant interaction between time and age (β =-0.005, 95%CI-0.008–-0.001; p for interaction=0.008) suggesting that younger patients at HT experienced faster CACS progression.

CACS progression is common post-HT, with a significant annual increase over time. Older recipient and donor age, CMV infection within the first year post-HT and ischemic cardiomyopathy as primary diagnosis for HT are associated with CACS progression. Younger patients at HT exhibited a faster rate of CACS progression. These findings emphasize the need for long-term cardiovascular risk management in HT patients. The clinical impact of CACS progression in HT patients remains unclear, warranting future research on its prognostic value and potential as a therapeutic target.Table 1

baseline characteristics