Background: The Micra leadless pacemaker has a high rate of procedural success and has proven to be safe and effective. However, well defined metrics to predict the long-term electrical performance of the device are lacking.
Objective: To formulate a predictive model for long-term electrical performance of Micra in order to aid clinicians with procedural decision-making regarding device repositioning.
Methods: We identified implanted Micra patients from the investigational device exemption study, continued access study, and post-approval registry with electrical parameter data (n=1848). The primary endpoint was an elevated pacing capture threshold (PCT) >2.0V at 0.24 ms, an increase of >1.5V in PCT from implant, or system revision due to elevated PCT, at any time within 12 months post implant. Regression analysis was performed to identify predictors of the primary endpoint.
Results: The primary endpoint was met in 293 patients, including 275 patients with an elevated PCT, 122 with an increased PCT, and 10 with a system revision, with some meeting multiple criteria. Of the 293 patients, 48 (16.4%) had a PCT >2V at implant. Predictors associated with elevated PCT in univariate analysis were subjected to multivariable regression modeling. Dialysis, history of myocardial infarction, implant impedance <500 ohms, and PCT at implant ≥2V at 0.24 ms were independent predictors of the primary endpoint (Figure).
Conclusion: History of myocardial infarction, need for dialysis, elevated PCT and low impedance at implant were independent predictors of elevated PCT or system revision. These metrics represent the foundation for a simple bedside tool to aid in procedural decision making.