Pacemakers and Bradyarrhythmias in Diabetic Mellitus

Dr. Deep Chandh Raja, Selva Maheshwari

¹Cardiologist and Clinical Lead of Cardiac Electrophysiology, Kauvery Heart Rhythm Services, Chennai

²Physician Assistant, Unit of Cardiac Electrophysiology, Kauvery Heart Rhythm Services, Chennai

Background

Diabetes mellitus is increasing in prevalence in India and thereby places a significant burden of on our health care system. Importantly, diabetes mellitus is an important risk factor for cardiovascular diseases. Several cardiovascular disorders are a complication of diabetes mellitus like coronary artery disease, peripheral artery disease, diabetic cardiomyopathy, heart failure, and stroke. These cardiovascular complications of diabetes mellitus and the disease per se can lead to both brady- and tachy-arrhythmias [1].

Cardiovascular autonomic neuropathy in diabetes and risk for arrhythmias

Cardiovascular autonomic neuropathy (CAN) is common among patients with diabetes mellitus. Patients with CAN have an increased risk of mortality. CAN manifests as tachycardia, prolonged QT interval, postural hypotension, exercise intolerance, and coronary vasomotor dysregulation. Hence, CAN increases the risk of cardiovascular complications including sudden cardiac death. Increased sympathetic activity and derangement of inflammatory markers can also contribute to CAN. The neural pathways that are responsible for inotropic, lusiotropic, chronotropic and dromotropic regulations of the heart can get deranged because of impaired baroreceptor control secondary to CAN. This can be measured in the form of heart rate variability (HRV). HRV can be reduced in patients with diabetes mellitus and is directly linked to increased incidence of atrial fibrillation, ventricular tachycardia and brady arrhythmias [2].

Electrophysiological mechanisms underlying cardiac brady- arrhythmias in Diabetes Mellitus

Sodium channel activation is responsible for conduction velocity. This conduction velocity results in spread of voltage current through gap junctions from one cardiomyocyte to the other. This conduction velocity gets slowed in diabetes due to hypoinsulinemia, insulin resistance and resultant electrolyte disturbances. Moreover, cardiac fibrosis is seen in diabetic cardiomyopathy. This can lead to reduced conduction and propagation of the action potentials. As a result, slowing of SA node and AV node conduction velocities can cause SA node and AV nodal block and hence brady arrhythmias. Slowing of conduction velocities could also be due to autonomic neuropathy. Patients with diabetes mellitus can also complain of syncope after a meal, which is called postprandial syncope period. These patients need to be evaluated for coronary artery disease. Impaired cardiovascular reflexes can also cause orthostatic and postprandial hypotension in patients with diabetes mellitus. There also have been anecdotal reports of postprandial complete heart block in these patients. Electrophysiology studies can help under the mechanisms of AV block in these patients. An increase in extracellular potassium secondary to renal diseases or medications is known to slow conduction velocity in the AV node and infra-Hisian conduction system. Eventually, complete AV block can occur in patients with hyperkalaemia [3].

Diabetes Mellitus and Complete Heart Block

Symptomatic bradyarrhythmias can occur in diabetic patients because of a complete heart block. Permanent pacemaker implantation is the standard treatment for symptomatic patients. In a Chinese study with 113 patients with symptomatic bradyarrhythmias requiring pacemaker, diabetes mellitus and dyslipidaemia were the most significant predictors. In a small study from Eastern India involving 37 patients requiring pacemaker implantation, the most common cause was AV block in 65% of patients, sinus node dysfunction in 27% of patients and trifascicular blocks in 5% of patients. Bradycardia was associated with hypertension in 60% of patients and diabetes mellitus in 22% of patients in this study.4

Pacemakers in Diabetic Patients with Acute Coronary Syndrome

High grade AV block is associated with bad outcomes in patients with myocardial infarction. In a study of patients presenting with myocardial infarction from the hormone housing outcomes with revascularization and stents in acute myocardial infarction trials who underwent primary PCI, the presence of high-grade AV block was detected in 2% of patients. Diabetes mellitus was the important predictor of high-grade AV block in addition to increased age, and right coronary artery involvement in this study. The mortality rate was significantly higher in patients with AV blocks [5].

Diabetes Mellitus in Elderly Patients with Pacemaker:

In a paper in the study reporting prevalence of diabetes in elderly patients with pacemakers, patients with diabetes mellitus accounted for 11% of the patients. In addition, diabetes mellitus had a higher risk of 1.34-fold (p < 0.01) for pacemaker procedures [6].

Complete Heart Block in diabetic nephropathy

In a study of patients with diabetes mellitus, the prevalence of chronic kidney diseases was 38% in the period from 2007-2012. In this study patients with chronic kidney diseases and with a pacemaker, the mortality rates were higher when compared with chronic kidney disease patients without a pacemaker. Of the patients who received renal replacement therapy, those with pacemakers had a higher mortality rate. Around 24 deaths were noted per 100 patient-years in patients on dialysis and pacemakers. The probable reasons could be a higher incidence of cardiovascular diseases, infection, and older age in the subset [7].

Pacemaker Infections in Diabetes Mellitus

Pacemaker infection is the Achillesâ€™ heel for device implants within the heart. Patients with diabetes mellitus have an even more increased incidence of cardiac device infection. Pacemaker pocket infection to the tune of 70% and lead endocarditis to the tune of 23% was the most common presentation in a study of 189 patients in the US. S. aureus, and coagulase-negative Staphylococci were detected in 30 and 40% patients, respectively in those patients with device-related infections. Almost all these patients underwent complete device removal. Cardiac device-related infections increase the risk of in-hospital death by two-fold. The other complications that can be noted in diabetic patients after a pacemaker implant include pocket hematoma due to antiplatelet use, lead-related endocarditis, and delayed healing of the wound. Persistent pacing of the right ventricle can also lead to heart failure in these patients due to concomitant diabetic cardiomyopathy [8].

Conclusion

Diabetic patients have higher than a usual predilection for bradyarrhythmias. This is mainly due to cardiac autonomic neuropathy and diabetic cardiomyopathy. These patients may require pacemaker implantation for either high-grade heart blocks or sinus node dysfunction. Though the technique of implantation is the same as that for the general population of pacemakers, the incidence of device infections is higher than usual in the subset of patients.

References

1.Bhar-Amato J, et al. Ventricular Arrhythmia after acute myocardial infarction: ‘the perfect storm. Arrhythm Electrophysiol Rev. 2017;6:134-139.

2.Serhiyenko VA, et al. Cardiac autonomic neuropathy: Risk factors, diagnosis and treatment. World J Diabetes 2018;9:1-24.

3.Tse G, et al. Molecular and electrophysiological mechanisms underlying cardiac arrhythmogenesis in Diabetes Mellitus. J Diabetes Res 2016;2016:2848759.

4.Vilas Yadavarao Kanse DSC, et al. Clinical profiles and outcomes of patients undergoing pacemaker implantation. J Med Soc. 2015;29:40-44.

5.Catarina Ferreira PM, et al Diabetes Mellitus is an independent predictor of atrioventricular block and need of pacemaker in acute coronary syndrome. Portuguese Soc Cardiol Acute Coronary Syndrome Registry.

6.Ozcan KS, et al. Pacemaker implantation complication rates in elderly and young patients. Clin Interv Aging 2013;8:1051-4.

7.Vanerio G, et al. Mortality in patients on renal replacement therapy and permanent cardiac pacemakers. Int J Nephrol. 2014;2014:284172.

8.Voigt A, et al. Rising rates of cardiac rhythm management device infections in the United States: 1996 through 2003. J Am Coll Cardiol. 2006;48:590-1.

Dr. S. Deep Chandh Raja

Cardiologist and Clinical Lead of Cardiac Electrophysiology

Pacemakers and Bradyarrhythmias in Diabetic Mellitus