Heart rhythm 2017 07 12() pii S1547-5271(17)30853-6
Diabetes is independently associated with increased risk of sudden cardiac arrest (SCA), with a need to identify novel methods for risk stratification. Diabetics can develop autonomic dysfunction which has been associated with increased risk of ventricular arrhythmogenesis, and manifests as reduced heart rate variability (HRV). However, previously published studies have not accounted for resting heart rate (HR), important from both pathophysiologic and prognosticating standpoints.
We sought to evaluate autonomic remodeling of the sinus node response in SCA and diabetes while accounting for HR.
We performed a case-control study in which SCA cases (age 35-59, 2002-2014) from the ongoing Oregon Sudden Unexpected Death Study (catchment population 1 million), and archived 12-lead ECGs performed prior to the SCA event were compared to geographical controls. Short-term HRV was calculated from digitized 10-second ECGs using established methods. We analyzed 313 subjects (mean age 52.4±5.3; 70.4% male) and compared 4 groups: 111 diabetics (49 cases, 62 controls) and 202 non-diabetics (80 cases, 122 controls).
Covariance analysis showed an absence of the expected interaction between HRV and HR (HRV-HR) in diabetic patients with SCA (regression slope -0.008, CI -0.023 to 0.0071, p=0.26). This finding, unique to this population of diabetic SCA cases, was not detected using traditional HRV measures.
By incorporating resting heart rate in this analysis, we observed that this population of diabetics with SCA had loss of the expected HRV-HR relationship. This potentially novel, non-invasive risk measurement warrants further investigation, especially at the level of the individual patient.