Improvement of Microvascular Ischemia by Atrioventricular Sequential Pacing in Non‐Obstructive Hypertrophic Cardiomyopathy
Muthiah Subramanian, Radhika Manukonda, Sachin Yalagudri, Daljeet Kaur Saggu, Sridevi Chennapragda, Calambur NarasimhanABSTRACT
Background
Therapeutic options for symptomatic non‐obstructive hypertrophic cardiomyopathy (nHCM) remain limited. We investigated whether right ventricular apical (RVA) pacing with optimal atrioventricular delay (AVD) can improve myocardial oxygen supply–demand mismatch, assessed using coronary sinus (CS) lactate as a marker of microvascular ischemia.
Methods
Patients underwent atrial pacing at 70% of target heart rate followed by AV sequential pacing at individually optimized AVD. CS lactate levels were measured at baseline, during atrial pacing, after washout, and during AV sequential pacing.
Results
Baseline CS lactate was 0.55 ± 0.15 mmol/L and increased to 1.13 ± 0.29 mmol/L during atrial pacing. After washout, levels returned to near baseline (0.59 ± 0.21 mmol/L). During AV sequential pacing at optimal AVD (142.8 ± 20.6 ms), CS lactate decreased to 0.86 ± 0.31 mmol/L, showing a significant reduction compared to atrial pacing ( p = 0.026). In 15 of 18 patients, CS lactate decreased during AV pacing compared with atrial pacing.
Conclusions
AV sequential pacing at optimized AVD reduces CS lactate during exertion in most patients with nHCM, suggesting improved myocardial oxygen balance and reduced microvascular ischemia.