SAN FRANCISCO – In systemic sclerosis, more than 1,190 ventricular ectopic beats per 24 hours of Holter monitoring was 100% sensitive and 83% specific for sudden cardiac death or defibrillator implantation within a year in a prospective cohort study from the Catholic University of the Sacred Heart in Rome.
Twenty-four hour Holter monitoring needs to be “part of the routine evaluation in SSc [systemic sclerosis] with suspicious cardiac involvement” so that patients get implantable cardioverter defibrillators (ICDs) in time, said investigator Dr. Giacomo De Luca, a rheumatologist at the university.
Dr. Giacomo De Luca
Arrhythmias secondary to myocardial fibrosis are killers in SSc and sometimes strike patients with mild heart symptoms such as dyspnea that are easily mistaken for lung involvement, and patients who fall outside of traditional ICD indications such as ejection fractions below 35%. Because of that, “better risk stratification is desperately needed” to catch patients early “and prevent sudden cardiac death [SCD],” Dr. De Luca said at the annual meeting of the American College of Rheumatology.
Holter monitoring isn’t a part of routine SSc workup, but Dr. De Luca and his team think it might solve the arrhythmia problem. Ventricular ectopic beats (VEBs) over 1,190 per 24 hours have an “excellent positive predictive value. [They are a] warning biomarker of major arrhythmias,” he said.
The conclusions come from 100 SSc patients with new-onset cardiac symptoms, generally palpitations and mild dyspnea, but also some with chest pain or heart failure signs. The subjects wore Holter monitors for 24 hours and then were followed for a mean of 2 years.
At baseline, 56 patients had Holter abnormalities. VEBs were the most common, present in 24 patients at a “strikingly high” mean of 2,046/24 hours. The number of VEBs correlated with cardiac troponin T (cTnT) levels and inversely correlated with left ventricular ejection fractions.
The team also found 19 patients with supraventricular ectopic beats, 14 with episodes of supraventricular paroxysmal tachycardia, and 11 with runs of nonsustained ventricular tachycardia, but those problems didn’t prove to be predictors of SCD.
During follow-up, seven patients met the study’s combined primary endpoint of SCD or ICD implantation. Five died and two had implants at a mean of 8.5 months. The age range was 32-77 years, and median baseline ejection fraction was 40%, but ejection fractions ranged widely and were normal in some, indicating that they don’t reliably predict SCD in SSc patients. None of the seven subjects had pulmonary arterial hypertension; it was ruled out by right heart catheterization.
Compared with the overall cohort, the seven patients who met the primary endpoint had lower ejection fractions and higher numbers of VEBs – all were above 1,000/24 hours at baseline – plus higher levels of cTnT and NT-proBNP [N-terminal prohormone brain natriuretic peptide].
The 1,190 VEBs/day cutoff emerged on a receiver operating characteristic (ROC) analysis that proved robust (AUROC = 0.94, P less than .0001); cTnT above 0.014 ng/mL and right bundle branch block were independent predictors of VEBs above the cutoff, but prolonged baseline QT intervals had no prognostic value.
The investigators had no disclosures.