Candidate for the Lee B. Lusted Student Prize Competition
Purpose: Cardiac implantable electronic device (CIED) leads fail stochastically, requiring the immediate implantation of a new lead(s). Because the total number of concurrently implanted leads (both functioning and failed) is subject to a maximum (i.e., five leads according to current guidelines), whenever a lead fails, it may be beneficial to extract this lead and/or any previously abandoned leads. Extraction, however, carries small but real life-threatening risks that increase in lead dwell time. Therefore, a tradeoff exists between maintaining space for new leads and avoiding risky extractions. Furthermore, surgical lead procedures involve a risk of infection. If an infection occurs, all implanted leads must be extracted. Hence, choosing to leave leads in place at the time of failures may result in risky, mandatory extractions. The purpose of this study is to determine a patient-specific extraction policy to maximize the expected lifetime of a single chamber pacemaker patient using a Markov decision process (MDP) model.
Method: We develop a MDP model to dynamically make extraction decisions at the time of lead failures as a function of patient and all lead ages. We also simulate this process to obtain prediction intervals on measures of interest including the expected patient lifetime and the likelihood of CIED-related deaths (as opposed to natural causes). Finally, we conduct comparisons to three heuristics commonly used in practice.
Results: Under the optimal policy, the extraction decision for each lead only depends on its age, patient age, its rank among the lead ages and the total number of implanted leads, i.e., the decision does not depend on the exact ages of all implanted leads. Figure 1 illustrates the optimal lead maintenance policy for a specific, single chamber pacemaker patient. Compared to the heuristic policies, the optimal policy significantly decreases CIED-related deaths and increases the expected lifetime, e.g., under the policy in Figure 1, a 60-year-old patient with failed leads of ages 20, 17, 12 and 2, observes an increase (decrease) of up to 1.5 years (7%) in their expected lifetime (likelihood of CIED-related deaths).
Conclusion: Cardiac leads are often referred to as “the weakest link” in implantable cardiac device treatment. Despite its importance, lead maintenance varies widely from practice to practice. We develop an approach that helps clinicians make patient-specific lead extraction/abandonment decisions optimally.
