Placement Of Cardiac PacemaKer Trial (POCKET)-RCT

Background: Implantation of a cardiac pacemaker may be indicated in patients with a significant bradycardia according to current guidelines.1 Annually, around 691 pacemakers per million inhabitants are implanted in Sweden.2 A pacemaker system consist of one or two leads connected to a device that is implanted beneath the collarbone.3,4 Vessel access is typically on the left side through the cephalic, axillary or subclavian vein. The pacemaker is inserted into a pocket. Routinely this pocket is just above the pectoral fascia (subcutaneously) or sometimes in skinny patients with a small amount of subcutaneous fat between the pectoral muscular layer (intramuscular). Even though technical developments have diminished the size of pacemakers markedly over time, complications due to superficial implants still do occur.5,6 Occasionally the device erode the skin and a complete extraction of the system is necessary. More frequently patients complain about the device being too superficial which sometimes require surgical repositioning of the device.5,6 The device may create discomfort, pain, and unsightly.5,6 The lateral corner of the device may disturb the shoulder movement, sleep and the leads can be turned within the pocket (Twiddler's syndrome). Minor branches from the supraclavicular nerves may result in discomfort. When vessels from the subcutaneous adipose tissue are distorted, extensive bruising may be bothersome and a large hematoma is a known risk of infection. The perfusion in the operation area is diminished and the amount of fat over device may be reduced to an extent that was unexpected at first implant. The change of device due to battery depletion can result in even less surrounding tissue. An alternative approach is an intramuscular placement of the device.7,8 This has been advocated by Kistler et al based on personal experience but there are neither systematic observational studies nor randomized controlled studies to support this approach.6 To the knowledge of the investigators no randomized controlled trial have addressed the question about the optimal placement of a bradycardia pacemaker.

Aim: To compare patient satisfaction with intramuscular placement of a pacemaker pocket to subcutaneous placement.

Research questions: Primary outcome: Is there a different in patient overall satisfaction (on a Visual Analog Scale (VAS)-scale between 0-10) with the pocket between patients with intramuscular placement of a pacemaker pocket and patients with subcutaneous placement at 24 months after implant? Secondary outcomes: Complications (revision of pocket, dislodgement, hematoma requiring surgery, infection (local/systemic). Patient reported satisfaction at 1, 12, 24 months (overall satisfaction, pain, discomfort, degree of unsightly look, movement problems due to device, and sleep problems due to device). Pacemaker nurse judgement of unsightly look of the pacemaker pocket (month 1, 12, and 24). Picture of pocket (1, 12, 24 months) judged by an experienced implanting physician who is blinded to the group allocation and has not operated on the patient.

Method: Power analysis: the investigators performed a power analysis based on expectations and clinical experience of the research group. Figure 1 shows two hypothetical truncated lognormal distributions of patient overall satisfaction with the pacemaker, where median overall satisfaction of the intramuscular and the subcutaneous group are assumed to be 2.4 and 4, respectively. Monte Carlo-simulations from these distributions showed that a total of 200 patients, 100 in each arm, would yield a statistical power of 90% for Mann-Whitney U-test at a significance level of 0.05.

In total, 200 consecutive patients with indication of are expected to be randomized in the study (100 patients in each arm, intramuscular vs subcutaneously). In Region Gavleborg , the annual primary implant volume of bradycardia pacemakers is approximately 220.