Arrhythmias, autonomic function predict unstable angina risk

[Hero]

Ventricular arrhythmias (VA) and heart rate variability (HRV) should be taken into account when assessing patients with unstable angina, Italian cardiologists say.

Their recommendation is based on a multicenter prospective study in which both parameters emerged as strong predictors of in-hospital and medium-term mortality, independently of classical risk factors.

The Stratificazione Prognostica dell'Angina Instabile Study included 543 consecutive patients admitted to 17 cardiology centers in Italy with a diagnosis of unstable angina but preserved left ventricular function. All patients underwent 24-hour Holter monitoring and were followed-up for 6 months.

Gaetano Lanza (Università Cattolica del Sacro Cuore, Rome, Italy) and co-authors, writing in the journal Heart, reveal that eight (1.5%) patients died in hospital and 32 (5.9%) died during follow-up, including 29 deaths due to cardiac causes.

A number of baseline ECG characteristics strongly predicted outcomes, the researchers report. After adjusting for multiple clinical and laboratory variables, both complex VA and frequent extrasystoles were strongly predictive of death in hospital and at follow-up.

In addition, patients with poor HRV – as indicated by R–R interval, low-frequency amplitude, and low-to-high frequency ratio – were significantly more likely to die in hospital or during follow-up than those with good HRV. Indeed, in multivariate analysis, a reduced low-frequency amplitude was consistently and independently associated with fatal events.

"Indeed, these variables can identify patients at extremely low risk and those at high risk of in-hospital and 6-month death, and therefore should be considered in risk stratification of patients with non-ST-segment elevation unstable angina," the team concludes.