Prevalence and long-term prognosis of patients with ‘narrower than normal’ QRS complexes

Very narrow QRS have been reported in sudden death survivors but prevalence and prognosis role of narrow QRS is unknown.

546 healthy men between 50 and 60 years (group 1) and 373 similar patients with coronary artery disease (368 men, group 2) underwent signal averaged ECG (SA-ECG) allowing precise measurement of QRS duration. All cause-mortality was determined after 18 ± 3 years follow-up. Mean QRS duration was 97 ± 13 ms in group 1 and 103 ± 16 ms in group 2. Tenth percentile was 84 ms in group 1 and 85 ms in group 2. All cause-mortality in group 1 was 10.4% (57/546): 6/85 in case of QRS <85 ms (7%) and 2/23 (9%) in case of QRS >120 ms (ns). HR for all-cause mortality was 0.75 (95% CI 0.32–1.76, P = 0.52) for QRS <85 ms and 0.86 (95% CI 0.21–3.53, P = 0.84) for QRS >120 ms. All cause mortality in group 2 was 29% (109/373): 7/44 in case of QRS <85 ms (16%) and 22/44 (50%) in case of QRS >120 ms (P = 0.002). HR for all-cause mortality was 0.65 (95% CI 0.29–1.45, P = 0.29) for QRS <85 ms and 1.73 (95% CI 1.02–2.94, P = 0.05) for QRS >120 ms.

QRS duration <80–85 ms can be observed in a significant proportion of middle-aged healthy males and in similar patients with ischemic heart disease. Narrow QRS were not linked to prognosis in any group.