Ambulatory Holter Findings in Patients with Palpitations and Structurally Normal Heart: A Prospective Study of the Prevalence and Patterns of Ventricular and Supraventricular Arrhythmias

Background/Objectives: Palpitations are among the most common reasons for cardiology referrals. Despite widespread use of ambulatory cardiac monitoring, contemporary data from the Middle East are scarce. Extended Holter monitoring provides detailed evaluation of arrhythmia burden, autonomic regulation, and symptom–rhythm correlation in routine clinical practice. Methods: We conducted a prospective observational study of consecutive patients presenting with palpitations who underwent 24–96 h ambulatory Holter monitoring at a cardiology outpatient clinic in Saudi Arabia in 2025. Demographic and clinical characteristics, comorbidities, medication use, echocardiographic parameters, heart rate variability (HRV), ventricular and supraventricular ectopy, tachyarrhythmias, and symptom diary activations were systematically evaluated. Results: Among 251 patients (mean age 41.9 ± 16.4 years; 35.5% male), Holter monitoring showed excellent recording quality (mean analyzable time 98.7 ± 9.5%). Premature ventricular contractions (PVCs) were detected in 53.4% of patients, but burden was low (median 0.0%, IQR 0–0.1%), with only 4.4% exceeding 10%. Atrial premature contractions (APCs) were common (92.0%), though usually low-burden (median burden 0.0%, IQR 0–0.1%); atrial fibrillation and supraventricular tachycardia were rare (0.8% each). Symptom diary activation occurred in 116 patients (46.2%), with 996 events; most (87.9%) correlated with sinus tachycardia, while only 8.6% correlated with PVCs and 2.6% with APCs. In the remaining 53.8% of patients, no symptom–rhythm correlation was documented during monitoring. Heart rate variability showed expected age-related changes. Conclusions: In this predominantly young cohort, Holter monitoring revealed frequent low-burden atrial and ventricular ectopy, whereas clinically significant tachyarrhythmias were uncommon. Holter monitoring up to 96 h provided a diagnostic yield in approximately 50% of patients and should be considered a first-line screening tool. Patients without diagnostic findings may require prolonged monitoring using external or implantable devices.