ABSTRACT: Aims: It is largely unknown whether cancer patients seen in routine care show ventricular arrhythmias in 24 h electrocardiograms (ECGs), and whether when they are detected they carry prognostic relevance. Methods and Results: We included 261 consecutive cancer patients that were referred to the department of cardiology for 24 h ECG examination and 35 healthy controls of similar age and sex in the analysis. To reduce selection bias, cancer patients with known left ventricular ejection fraction <45% were not included in the analysis. Non-sustained ventricular tachycardia (NSVT) episodes of either ≥3 and ≥4 beats duration were more frequent in cancer patients than controls (17% vs. 0%, p = 0.0008; 10% vs. 0%, p = 0.016). Premature ventricular contractions (PVCs)/24 h were not more frequent in cancer patients compared to controls (median (IQR), 26 (2-360) vs. 9 (1-43), p = 0.06; ≥20 PVCs 53% vs. 37%, p = 0.07). During follow-up, (up to 7.2 years, median 15 months) of the cancer patients, 158 (61%) died (1-/3-/5-year mortality rates: 45% [95%CI 39-51%], 66% [95%CI 59-73%], 73% [95%CI 64-82%]). Both non-sustained ventricular tachycardia of ≥4 beats and ≥20 PVCs/24 h independently predicted mortality in univariate and multivariate survival analyses, adjusted for all other univariate predictors of mortality as well as relevant clinical factors, including cancer stage and type, performance status (ECOG), prior potentially cardiotoxic anti-cancer drug therapy, coronary artery disease, potassium concentration, and haemoglobin (multivariate adjusted hazard ratios: NSVT ≥4 beats [HR 1.76, p = 0.022], ≥20 PVCs/24 h [HR 1.63, p < 0.0064]). Conclusions: NSVT ≥4 beats and ≥20 PVCs/day seen in routine 24 h ECGs of patients with cancer carry prognostic relevance.
